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Home , Discoglossus pictus, Pallium (neuroanatomy)

Research Article • DOI: 10.2478/s13380-011-0010-9 • Translational Neuroscience • 2(1) • 2011 • 79-89 Translational Neuroscience

F. K. STUDNIČKA (1894): FISHES AND ALSO HAVE THE Miloš Judaš* Abstract University of Zagreb School of Medicine, The aim of this paper is to provide translation of probably the first report (Studnička 1894) demonstrating that Croatian Institute for Research, the telencephalon of all vertebrate taxa (including fishes and amphibians) is characterized by the presence of Salata 12, 10000 Zagreb, Croatia the cerebral cortex (pallium). This report was one of those initiating a century-long and still not fully resolved discussion concerning homologies of various pallial subdivisions in different vertebrate taxa and probably the first to draw attention to the importance of careful study of the pallium in representatives of agnathans (Cyclostomes) such as lampreys (Petromyzonts) and hagfishes (Myxinoids). This article also briefly reviews the current status of comparative research on vertebrate telencephalon, and provides historical notes which position Studnička’s report in its historical context. Keywords • Comparative neuroanatomy • Cyclostoma • Evolutionary neuroscience • Hagfish • Lamprey • Myxine • Pallium • Petromyzon

Received 15 March 2011 © Versita Sp. z o.o. accepted 15 March 2011

1. Introduction convincingly demonstrated that Agnatha are the telencephalon is the rostral expansion of monophyletic and bona fide members of the the brain including pallium and subpallium. The past decades have wittnessed major vertebrate clade [4,5]. Thus, lampreys and Pallium is the dorsal part of the telencephalon advances and significant changes in our hagfishes are currently treated as members that arises from the rostral, dorsal neural folds, interpretation of the of the cyclostome radiation and the latter as including , cortex, and part of the of vertebrates and their cerebral cortex [for one of the four major vertebrate radiations [6]. comprehensive reviews, see 1-3]. A brief [1]. Therefore, the four major vertebrate A century ago, at the time of Studnička’s overview of current and generally accepted radiations are the agnathans/cyclostomes report, it was a usual practice to designate concepts would seem appropriate to set and three radiations of gnathostomes which fishes and amphibians (Anamniota) as „lower“ the context for the report translated here comprise: chondrichthyans (ratfishes, sharks, vertebrates, while the Amniota – or even and its historical relevance. However, the skates, and rays), actinopterygians (ray-finned only – were considered as „higher“ general reader will probably also benefit if fishes), and sarcopterygians (fleshy-finned vertebrates [7]. Thus, previously influential we first define some basic terms. fishes and their four-limbed derivatives, the theory of the rhinencephalon (smell-brain) are Deuterostome with a notochord. tetrapods) [1]. The tetrapods are vertebrates suggested that the telencephalon of fishes Extant chordates comprise three major groups: with four feet, generally including amphibians, is largely dominated by secondary olfactory urochordates (tunicates, or sea squirts), reptiles, , and mammals. Furthermore, input, and ascending sensory systems reaching cephalochordates (e.g., Branchiostoma/ most of the vertebrate taxa are anamniotes the telencephalon were believed to exclusively Amphioxus), and vertebrates (or craniates) [1]. (their embryos lack an amniotic membrane). characterize amniotes, or even mammals only While Acrania are chordates with no obvious In contrast, amniotes have an amniotic [for review, see 7]. This theory is clearly echoed head (such as the lancelet, Branchiostoma, membrane that encases the embryo in in the discussion between Studnička and previously known as Amphioxus), Craniate is amniotic fluid during development; thus, Burckhardt at the end of the report translated a with fully developed head, but with amniote vertebrates do not need to lay their here. or without jaws. Thus, while Cyclostomes or eggs in water for development [1]. While fishes In the modern comparative research, that Agnatha are jawless lampreys (Petromyzontids) and amphibians are anamniotes, the amniotes old-fashioned Scala naturae metaphor of and hagfishes (Myxinoids) with a circular are the nonamphibian tetrapod land vertebrate the vertebrate brain climbing slowly up the mouth, the Gnathostomes are vertebrates descendants of ancestral sarcopterygians, ladder of progres from fish to human has with true jaws. Recent molecular analysis has i.e. reptiles, birds and mammals [1]. Finally, been replaced by the common theme of a

* E-mail: [email protected]

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largely conservative Bauplan of vertebrate [6]: (a) the best comparison of the mammalian but remains restricted to two pallial layers [7]. brain organization, upon which innumerable general cortex (including isocortex) is with the While secondary olfactory projections are also variations are independently generated along avian hyperpallium and dorsolateral cortex and extensive in the lamprey pallium [15], all hagfish various major phylogenetic lines [7, 8]. with reptilian dorsal cortex; (b) the changes pallial layers receive additional dorsal thalamic While a dorsal part of the pallium lying during the transition from the reptilian to avian input [14,16]. In addition, there are reciprocal between the medial and lateral pallia has been were not dramatic, since recognition connections both with the and identified in all Gnathostoma, the question of homologous regions is fairly straightforward; the dorsal thalamus [7]. The lamprey pallium of whether any or all of the dorsal pallium and (c) the reptile to transition is also receives dorsal thalamic input [15]. The in various anamniotes is homologous to the marked by a massive hypertrophy of the dorsal fact that diencephalic sensory input reaches nonlimbic pallial areas in amniotes is one of (general) cortex. Finally, assuming that the the pallium in both lampreys and myxinoids the most important unresolved questions forebrain of the common tetrapod ancestor demonstrates that the telencephalon (and in comparative neurobiology [1]. Note that was similar to that of extant amphibians, the pallium) is not exclusively of olfactory nature this question currently is not focused on the -reptile transition was marked by as the old smell-brain theory would predict [7]. existence of the cerebral cortex in general, but segregation of pallial fields: the medial pallium Amphibians. Modern amphibians rather on the existence of possible anamniote gave rise to the medial and dorsal cortices (Lissamphibia) form the three orders: Anura homologues for six-layered of of reptiles, the dorsal and lateral pallia gave ( and toads; 29 families, about 4086 amniotes (and especially mammals). In rise to the pallial thickening and most of the species), Urodela (newts and salamanders; 10 attempting to fully resolve these questions, lateral cortex, and the ventral part of the lateral families, about 545 species), and Gymnophiona comparative neuroanatomists have focused pallium gave rise to the DVR and overlying (caecilians; 6 families, 170 species) [17]. It is on several defining features of the nonlimbic lateral and amygdalar cortices [6]. also assumed that the lungfishes (Dipnoi – 6 pallium in amniotes (which in mammals species) are the living sister group to tetrapods consists of the neocortex), including the and the closest nontetrapod relatives of receipt of ascending sensory projections from 3. Evolution and homologies of modern amphibians [17,18]. In zoology and the diencephalon and the absence of afferent cerebral cortex in anamniotes evolutionary biology, amphibians have always projections from the olfactory bulb [1]. (fishes and amphibians) played a problematic role, and the evolutionary status of the of amphibians has always Fishes. The telencephalon of all fishes includes created difficulties [17]. The brains of frogs, and 2. Evolution and homologies of a pallium and a subpallium, and pallium also especially of caecilians [19] and salamanders cerebral cortex in amniotes receives non-olfactory inputs [7,10]. For the [20], appear to be simpler than those of (reptiles, birds and mammals) purpose of this article, it is sufficient to focus on chondrichthyans and osteichthyans, and even pallium of agnathans. All hagfishes are marine of cyclostomes in some respects. However, The reptilian telenc ephalon contains two major scavengers, which feed by entering the body today it is widely accepted that lissamphibians divisions, the pallium (telencephalic roof) and cavities of dead or dying fishes; lampreys are have undergone secondary simplification the subpallium. The pallium includes the true parasites, which attach to the body surface which arises from „paedomorphosis“ and medial, dorsal, and lateral cortices, the pallial of other fishes, and (while some lampreys is related to enlarged genome and cell size thickening, dorsal ventricular ridge (DVR), and are marine) all spawn in freshwater rivers. [17, for review, see 21 and 22] . On the other several amygdaloid nuclei [6]. The lateral cortex Lampreys undergo a larval (ammocoete) stage hand, the degree to which the morphology of is the primary target of the main olfactory followed by a metamorphosis to the adult the amphibian telencephalon is primitive or bulb, and reciprocates this connection; the form [1]. The brain of hagfishes is strikingly secondarily simplified remains undecided [17]. medial cortex is generally regarded to be a complex, in contrast to that of lampreys, The amphibian pallium was traditionally hippocampal region; the dorsal cortex appears although hagfishes do not have complex divided into a medial, dorsal, and lateral pallial to be a general (nonhippocampal, nonolfactory behavioral repertoires, and their visual system fields [23], but recent gene expression data cortex) cortical area [for review, see 6]. is markedly reduced [1]. Recent studies on the led to a subdivision of the lateral pallium into There is general agreement about the forebrain of petromyzontids and myxinoids a lateral and ventral pallium as different types homologues between the reptialian and avian have been well summarized in several reviews [8]. In addition, the rostral portion of the cortical regions [for review, see 6], and the [7,11-13]. The myxinoid pallium apparently pallium appears to be a pallial region of its lateral, dorsal, and medial cortices are generally does not show three pallial divisions typical of own [17]. Finally, recent connectivity data lead compared to the piriform, general (nonolfactory, gnathostomes, but is rather homogeneously to conclusion that both the dorsal and lateral nonhippocampal), and hippocampal cortices organized as a cortex with five distinct pallia are comparable to those of the reptilian of mammals [6,9]. The available connectivity neuronal layers throughout [14]. Olfactory lateral cortex, wheres the medial pallium is and neurochemical data together indicate that bulb input is extensive in the hagfish pallium, comparable to both the reptilian medial and

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dorsal cortices [9, review in 6]. Briefly, one can In summary, the differences between any type of cerebral cortex in the so-called distinguish six areas of the pallium of frogs and amphibians on the one hand and mammals „lower vertebrates“ (fishes and amphibians salamanders, but the homologies and functions and birds on the other concern mostly – especially Petromyzonta and Myxine, of these pallial regions are largely unclear [17]. the connection between thalamus and as representatives of supposedly most Most authors agree that the medial pallium is pallium/cortex, the intra-telencephalic primitive, agnathan, fishes) was questioned. homologous to at least parts of the mammalian connections of the pallium/cortex, The report of Studnička, translated here, hippocampus (Ammon’s horn and subiculum) predominantly to the striatopallidum, and represents probably the first attempt to and that a dentate gyrus is lacking [17, 24]. the further differentiation, enlargement, reverse that theoretical attitude and to The lateral pallium in the traditional sense and specialization of pallial/cortical demonstrate that all vertebrates indeed is generally considered an olfactory pallium structures. This further differentiation of have at least some kind of the cerebral and homologous to the mammalian piriform the thalamocortical system apparently has cortex. Not surprisingly, that report initated cortex, while the function of the dorsal pallium occurred independently in mammals and a long and heated polemics, and echoes is unclear. It receives essentially the same birds originating from different reptilian of century-old arguments can be detected sensory and associative afferents as the medial ancestors [17]. even in certain present day discussions. It is pallium, but lacks extra-telencephalic and also interesting to note that the realization extra-pallial efferents; unimodal sensory areas that even the „lower vertebrates“ have a are lacking and the dorsal pallium appears to 4. Conclusion and introduction cerebral cortex came surprisingly late – in have integrative-associative and limbic but no to translation of Studnička’s the closing years of the XIX. century – that is, primary sensory functions [17]. report well after the introduction of major classical Thus, the amphibian dorsal pallium possesses neurohistological methods (Nissl, Weigert, no unimodal, topographically organized areas Preceeding remarks demonstrate that at and Golgi staining) and after the firm as found in the mammalian isocortex and the present there is a general agreement that establishment of the theory through avian hyper-, meso-, and nidopallium [25], and all vertebrates posses a cerebral cortex the seminal studies and monographs of is most probably homologous to the limbic- (pallium) and unresolved questions concern Wilhelm His, Auguste Forel, Camillo Golgi, associative cortex of mammals [17]. Finally, the exact homologies of various pallial Santiago Ramón y Cajal, Gustav Retzius and pallial premotor and motor areas are likewise components in different taxa. However, Arthur Van Gehuchten (for an extensive missing in amphibians as well as in lizards and at the end of XIX. century, most leading review, see [26, for an extensive review see turtles [17]. authorities questioned the very existence of 27].

References

[1] Butler A. B., Hodos W., Comparative Vertebrate Neuroanatomy. [8] Puelles L., Brain segmentation and forebrain development in Evolution and Adaptation, 2nd Edition, Hoboken, New Jersey: amniotes, Brain Res Bull, 2007, 55, 695-710 Wiley-Interscience, 2005 [9] Bruce L.L., Neary T.J., The limbic system of tetrapods: A comparative [2] Kaas J. H., Bullock T. H., Evolution of Nervous Systems. A analysis of cortical and amygdalar populations, Brain Behav Evol, Comprehensive Reference, Volume 2: Non-Mammalian Vertebrates, 1995, 46, 224-234 Oxford – San Diego: Academic Press, 2007 [10] Wullimann M.F., Mueller T., Teleostean and mammalian [3] Striedter G., Principles of Brain Evolution, Sinauer Associates, 2005 contrasted: Evidence from genes to behavior, J Comp Neurol 2004, [4] Furlong R. F., Holland P. W. H., Bayesian phylogenetic analysis 475, 143-162 supports monophyly of Ambulacraria and of cyclostomes, [11] Braun C.B., The sensory biology of lampreys and hagfishes: A Zoological Science 2002, 19, 593-599 phylogenetic assessment, Brain Behav Evol 1996, 48, 262-276 [5] Mallat J., Sullivan J., 28S and 18S rDNA sequences support the [12] Wicht H., The brains of lampreys and hagfishes: Characteristics, monophyly of lampreys and hagfishes, Mol Biol Evol, 1998, 15, 1706- characters, and comparisons, Brain Behav Evol 1996, 48, 248- 1718 261 [6] Bruce L.L., Evolution of the nervous system in Reptiles, In: Kaas J.H., [13] Wicht H., Northcutt R.G., The forebrain of the pacific hagfish: A Bullock T.H. (Eds) Evolution of Nervous Systems Vol. 2, Oxford-San cladistic reconstruction of the ancestral craniate forebrain, Brain Diego: Academic Press, 2007, 125-156 Behav Evol, 1992, 40, 25-64 [7] Wullimann M. F., Vernier P., Evolution of the nervous system in fishes, [14] Wicht H., Northcutt R.G., Telencephalic connections in the In: Kaas J.H., Bullock T.H. (Eds) Evolution of Nervous Systems Vol. 2, Pacific hagfish (Eptatretus stouti), with special reference tothe Oxford-San Diego: Academic Press, 2007, 39-60 thalamopallial system, J Comp Neurol 1998, 395, 245-260

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[15] Polenova O. A., Vesselkin N. P., Olfactory and non-olfactory [21] Gregory T. R., Genome size and developmental complexity, projections in the river lamprey (Lampetra fluviatilis) telencephalon, Genetica, 2002, 115, 131-146 J Hirnforsch, 1993, 34, 261-279 [22] Gregory T. R.,Variation across amphibian species in the size of the [16] Murakami Y., Uchida K., Rijli F. M., Kuratani S., Evolution of the brain nuclear genome supports a pluralistic, hierarchical approach to the developmental plan: Insights from agnathans, Dev Biol, 2005, 280, C-value enigma, Biol J Linn Soc 2002, 79, 329-339 249-259 [23] Northcutt R. G., Evolution of the telencephalon in nonmammals, [17] Dicke U., Roth G., Evolution of the Amphibian nervous system, Ann Rev Neurosci 1981, 4, 301-350 In: Kaas JH, Bullock TH (Eds) Evolution of Nervous Systems Vol. 2, [24] Westhoff G., Roth G., Morphology and projection pattern of Oxford-San Diego: Academic Press, 2007, 61-124 medial and dorsal pallial in the pictus [18] Brinkmann H., Denk A., Zitzler J., Joss J. J., Meyer A., Complete and the salamander Plethodon jordani, J Comp Neurol, 2002, mitochondrial genome sequences of the South American and 445, 97-121 the Australian lungfish: Testing of the phylogenetic performance [25] Reiner A., Perkel D. J., Bruce L. L., Butler A. B., Csillag A., Kuenzel W., of mitochondrial data sets for phylogenetic problems in tetrapod et al., Revised nomenclature for avian telencephalon and some relationships, J Mol Evol, 2004, 59, 834-848 related brainstem nuclei, J Comp Neurol, 2004, 473, 377-414 [19] Kuhlenbeck H., Zur Morphologie des Gymnophionengehirns, [26] Shepherd GM (1991) Foundations of the Neuron Doctrine. New York Jenaische Zeitschrift für Naturwissenschaften, 1922, 58, 453-484 – Oxford: Oxford University Press. [20] Herrick C. J., The Brain of the Tiger Salamander Ambystoma tigrinum, [27] Jacobson M., Developmental Neurobiology, Third Edition, New York Chicago: University of Chicago Press, 1948 – London: Plenum Press, 1991

TRANSLATION OF : such as Schulgin, Köppen (Köpen 1888, 1892), their brain is generally simpler than that of F. K. Studnička (1894) Adolf Meyer (Meyer 1892) and especially by Amphibians. That cortex was first depicted in Towards the history of the „Cortex Edinger (Edinger 1888). It has been realized figures published by Fulliquet (Fulliquet 1886), cerebri“. that one can homologize a large part of it and then described in detail by Burckhardt Anatomischer Anzeiger (i.e., the part located in the posteromedial (Burckhardt 1892, 1894a,b,c). He showed that 9(Suppl):193-197. part of hemispheres, along the fornix) – just like in reptiles – the Ammonic cortex with the well-known Ammonic cortex of is here also separated from the remaining The present report, originally entitled Zur mammals, which is known as an olfactory cortex. As one can conclude from Burckhardt’s Geschichte des „Cortex cerebri“, was delivered centre. In addition, it was demonstrated that illustrations, the Ammonic cortex is here better by F. K. Studnička in 1894, as a lecture on this formation is directly connected with the developed and contains more cells than the the 8. Meeting of the German Anatomical olfactory bulb. Until recently, it was generally remaining portion of the hemispheric cortex, Society held in Strassburg i. E., from 13. to thought that cortical formation does not which is formed only by separate groups of 16. May 1894 (during the Fifth Session of the exist in the prosencephalic hemispheres of neurons. meeting). It was subsequently published in Amphibians, until the studies of Nakagawa Thus, according to previous findings, Transactions (Verhandlungen) of that meeting, (Nakagawa 1891) demonstrated that in a lungfishes and amphibians were the lowest in a supplement volume to the official journal certain Urodele (Spelerpes ruber) there are vertebrates possessing the cerebral cortex in of the society, the Anatomischer Anzeiger. small groups of neurons in the medial part their telencephalic hemispheres. However, the Gentlemen! Let me be permitted to report of the pallium which are separated from studies I have performed demonstrate that on the first appearance of the so-called gray the central (periventricular) grisea and may more or less distinct cerebral cortex is also „cortex“ in the prosencephalic hemispheres represent a primitive cerebral cortex. In his present in the hemispheres of Cyclostome of the series of vertebrates. The cerebral studies, Burckhardt (Burckhardt 1892) also brains. cortex of mammals was alredy known to old observed that in the Triton a small part of the But, before we can discuss that cortex, anatomists. However, its presence in the brain hemispheric pallium represents a probable it is necessary to clarify what exactly can of birds received its first detailed description homolog to the Ammonic cortex of higher be regarded as telencephalic hemispheres by Bumm (Bumm 1883). That it is also present animals. Finally, Oyarzun found scattered in the brain of Cyclostomes – especially of in the brain of reptiles, we have learned from neurons in outer layers of the amphibian Petromyzontids, which display a more ancestral Stieda’s work on the brain of turtles (Stieda pallium (Oyarzun 1890). pattern of organization. As you know, if we put 1875a,b). The cortex of reptiles, which are the It is quite peculiar that the cerebral cortex aside older views (e.g. of Johannes Müller), there lowest among Amniota, is quite interesting; it is present in the hemispheric pallium of are two views on the brain of Petromyzontids in has been recently studied by several authors, lungfishes (Dipnoi – esp. the Protopterus), as the current literature.

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According to the older view, presented in has to perform the function of the Now, I have observed that in that massive the publications of Burt Green Wilder (Wilder rudimentary pallium in addition to its own forebrain, the well developed cerebral cortex 1875, 1876, 1877, 1887), and especially of function. Well, of course, that can be decided composed of two layers of neurons (even three Ahlborn (Ahlborn 1883) and subsequently of only by further study of the development and layers in the medial part of the hemisphere) is S. P. Gage (Gage 1893) and my own (Studnička comparative anatomy of the so-called „Corpus present exactly in the same location in which 1894), the walls of the hemispheres (which striatum“. the above mentioned cell groups are observed contain the pallium) are in all their parts of the I will here only try to focus your attention to in the Petromyzon. same thickness, and the rostral part of the so- those brain parts which are situated between It is known that in any vertebrate in which called third ventricle is in the interhemispheric the hemisphere and the Tela, or (according to the hemispheric cerebral cortex is present space covered by the Tela chorioidea and partly the first view) between the Corpus striatum and (perhaps with the exception of Amphibians), the (i.e., rostrally) by the upper part of the Lamina the pallium (see Figure 1). You may observe Ammonic cortex is separated from the remaining terminalis (which partly corresponds to the that there is no cortex developed in that part, cortex and that this Ammonic cortex becomes Lamina supraneuroporica of Burckhardt). which (according to the second view) must relatively larger as we descend along the series According to the second view, first exposed belong to the pallium and represent a massive of vertebrates towards the lower forms. by Edinger (see, e.g., Edinger 1888) and accepted component of it. If we accept the first view, we As I tried to demonstrate in an earlier in the textbook of Wiedersheim (Wiedersheim have to regard that part as the inner margin publication (Studnička 1894), a certain kind of 1883 and subsequent editions), what was of the hemisphere; it is located at the same the cerebral cortex is present in hemispheres designated as „hemispheres“ by earlier authors place in which in other animals (e.g., already in of Cyclostomes which are homolog only to is in fact homologous to (Corpora reptiles) the fornix is situated. the most caudal part of hemispheres of higher striata) of Amniota, and just the Tela represents I believe that it will be ascertained beyond vertebrates. Let me put forward the hypothesis the pallium proper of the quite reduced and any doubt that these cell groups in the brain of that this entire cortex should be compared only un-paired prosencephalon. These authors Petromyzon represent a real cerebral cortex, if we with the Ammonic cortex of other vertebrates, interpret the brain of Petromyzon in the same compare it with a closely related brain of Myxine. and that it also represents an olfactory centre. way as Rabl-Rückhard has interpreted the brain The investigations of Retzius (Retzius 1893) Thus, Cyclostomes still do not possess other of (Rabl-Rückhard 1883). have demonstrated that in Myxine all forebrain types of cortical formations, which could serve The appearance of the grey hemispheric ventricles are almost completely obliterated. other functions. It is probable that here the cerebral cortex is mainly restricted to the hemispheric pallium. According to authors who accept the second view, that pallium is developed just as an epithelial membrane; therefore, one naturally cannot think of it as the cerebral cortex. According to authors who accept the first view, in contrast, the pallium is conceived as the massive wall and thus it is possible that cerebral cortex can develop within it. According to my investigations, Petromyzon really possesses in that part of the brain small groups of neurons, quite similar to those observed in the pallium of Protopterus or Spelerpes. Now, I regard these cell groups as real, although quite primitive cerebral cortex (these cell groups are not equally distinct in all analyzed specimens, and sometimes the cells were scattered through the hemispheric wall). To that one can put forward an objection, that it is quite possible for cerebral cortex to develop below the surface of the Corpus striatum, and not just within the pallium, and that that could be (if one accepts the second view) even quite possible because the Corpus Figure 1. Coronal section through the hemisphere of Petromyzon Planeri.

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entire hemisphere represents just a higher of the original report, see Supplement 1). of the Cornell University, married to Simon olfactory centre. Some of them appear as footnotes, and Gage, professor of anatomy and physiology at In favor of this interpretation of the cerebral others in parentheses in the text. Studnička Cornell University, and student of the famous cortex of cyclostomes as an olfactory centre often gives just an author’s family name Cornell professor Burt Green Wilder. The names speaks the following observation: this cortex without a bibliographic reference. He also of Ludwig Edinger and Gustav Retzius are is much better developed in the blind Myxine misspelled the names of certain authors – probably well enough known to any student (which also has a more developed olfactory e.g., Nakagava instead of Nakagawa). I have of neuroscience. I was not able to uncover apparatus) than in the Petromyzon which is traced relevant references in all such cases, full biographical data on Georges Fulliquet, endowed with the sense of vision. except for „Schulgin“ (mentioned in the text Max Köppen, Isaac Nakagawa, A. Oyarzun To conculde this short report, let me note without any additional data). Thus, I have and Robert Wiedersheim, However, Robert that the cortex of Petromyzon was alrerady added a complete new reference list including Wiedersheim was author of widely used and illustrated in the publication of Mss. Susanne citations given in full (and adding first names esteemed German Textbook of Comparative Phelps Gage (Gage 1894 – Plate VIII, Figs 105 of authors as well as full titles of old German Anatomy; A. Oyarzun arrived from Santiago and 106), and the cortex of Myxine was already scientific journals, to enhance their proper de Chile and performed the qouted study (although quite schematically) illustrated tracking and recognition), and corrected as under the guidance of Ludwig Edinger at the in two figures in the publication of Retzius was often necessary. Accordingly, I inserted Senckenberg’s Institute in Frankfurt am Main; (Retzius 1893). However, although these the proper references in brackets in the Isaac Nakagawa performed his research under authors included it in their illustrations, they present translation. To see how Studnička in the supervision of Professor Henry Fairfield did not conceive depicted structure as the fact quoted them, see the transcription of the Osborn in the Class of 1877 at the biological cerebral cortex. original report in the Supplement 1. Laboratory of Princeton College and the Note on authors: František K. Studnička list of Princeton alumni states that he was Discussion (1870 – 1955) was a renowned histologists, subsequently a B.Sc. at the Bacteriological the founder and first head of the Histological- Institute in Tokyo and subsequently a professor BURCKHARDT agrees that the forebrain of Embryological Institute at the School of in the Government Medical College at Sendai. lower fishes has exclusively olfactory functions. Medicine of the University J. E. Purkinje in However, that is exactly the reason not to accept Brno, and later at the Charles University in References quoted in Studnička’s the homology of cortex in prosencephalon Prague. Researchers cited by Studnička were: article: of lower fishes with the cortex of amphicoele Friedrich Ahlborn (1858 – 1937), zoologist Ahlborn, Friedrich (1883) Untersuchungen brains in which the cerebral cortex represents a from Göttingen; Anton Bumm (1849 – 1903), a über das Gehirn der Petromyzonten (Mit substrate for quite different functions. student of Bernhard von Gudden, professor of Taf. XIII-XVII u. 1 Holzschnitt). Zeitschrift für STUDNIČKA: I have really observed numerous psychiatry in Munich and director of psychiatric wissenschaftliche Zoologie 39(2):191-294. radially coursing nerve fibres in some cortical institutions in Deggendorf and Erlangen; Bumm, Anton (1883) Das Grosshirn der layers of the Myxine brain – thus, they may Rudolf Burckhardt (1866 – 1908), eminent Vögel (2 Tafeln - XXIV-XXV). Zeitschrift für belong to the olfactory radiation. The same zoologist, naturalist and palaeontologist of wissenschaftliche Zoologie 38:430-467. fibers were not so easily observed in the brain the University of Basel (where his father was Burckhardt, Rudolf (1892) Das of Petromyzon; however, on sections stained a Rector), who died as the director of the Centralnervensystem von Protopterus with the Golgi method, I was able to observe Zoological Station Rovigno (Rovinj, Istria – part annectens. Eine vergleichend-anatomische nerve fibers which originate from neurons of of Croatia); Adolf Meyer (1866 – 1950), a swiss- Studie. Mit fünf Tafeln. Berlin: Verlag von R. the „Cortex“ and stretch to the medial brain american neurologist and psychiatrist who Friedländer & Sohn, 1892, 92pp. regions. studied psychiatry at the University of Zurich Burckhardt, Rudolf (1894a) Die Homologien under Auguste Forel and neuropathology des Zwischenhirndaches und ihre Bedeutung Translator’s References: under Constantin von Monakow, and in für die Morphologie des Hirns bei niederen 1892 moved to United States; a German Vertebraten (Mit 1 Abb.). Anatomischer Note on references: In translating Studnička’s neuroanatomist and histologist Hermann Rabl- Anzeiger 9:152-155. report, I have tried to retain his style as Rückhard (1839 – 1905); Ludwig Stieda (1837 Burckhardt, Rudolf (1894b) Die Homologien far as possible, only turning the phrases – 1918), an eminent professor of anatomy des Zwischenhirndaches bei Reptilien und and sometimes breaking the sentences at the University of Dorpat (University of Vögeln (Mit 3 Abb.). Anatomischer Anzeiger when it was necessary to produce readable Tartu – Estonia) and University of Königsberg; 9:320-324. English. Studnička also used several, Susanna Phelps Gage (1857 – 1915) was Burckhardt, Rudolf (1894c) Zur vergleichenden rather inconsistent, methods for giving embryologist and comparative anatomist at Anatomie des Vorderhirns bei Fischen (Mit 5 bibliographic references (for transcription the Department of Histology and Embryology Abb.). Anatomischer Anzeiger 9:375-382.

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Edinger, Ludwig (1888) Untersuchungen Rabl-Rückhard, Hermann (1883) Das Grosshirn Additional references of authors cited über die vergleichende Anatomie des der Knochenfische und seine Anhangsgebilde by Studnička, closely related to the Gehirns, 1. Das Vorderhirn. Abhandlungen (Hierzu Taf. XII u. XIII). Archiv für Anatomie topic of his article der Senkenbergischen Naturforschernden und Physiologie (Anatomische Abtheilung) Gesellschaft in Frankfurt a/M 15:91-119. Jahrgang 1883, pp. 280-322. Translators Note: References listed below were Fulliquet Georges (1886) Recherches sur le Retzius, Gustav (1893) Das Gehirn und das not directly quoted by Studnička (and some of cerveau du Protopterus annectens, avec les Auge von Myxine (Tafel XXIV-XXVI). Biologische them were published after his initial report), planches I à V. Recueil Zoologique Suisse (1. Untersuchungen (Neue Folge) 5:55-68. but they are directly relevant to the topic of série) 3:1-130. Stieda, Ludwig (1875a) Ueber den Bau des Studnička’s article, were written by authors Gage, Susanna Phelps (1893) The Brain of centralen Nervensystems des Axolotl (Mit Tafel quoted by Studnička, and some of them were Diemyctylus viridescens, from Larval to XIX). Zeitschrift für wissenschaftliche Zoologie in fact published as parts of extensive and Adult Life, and Comparisons with the Brain 25(3):285-312. heated discussion originated by Studnička’s of Amia and of Petromyzon (with eight Stieda, Ludwig (1875b) Ueber den Bau des original report (see esp. Burckhardt 1894; plates). The Wilder Quarter-Century Book. centralen Nervensystems der Schildkröte 1895a,b; 1907; Rabl-Rückhard 1895; Studnička A Collection of Original Papers dedicated (Hieruz Tafel XXV u. XXVI). Zeitschrift für 1894; 1895a,b,c). to Professor Burt Green Wilder at the wissenschaftliche Zoologie 25(4):361-406. Burckhardt R (1894) Bemerkungen zu K.F. Close of his Twenty-fifth Year of Service in Studnička FK (1894) Zur Lösung einiger Studnička’s Mitteilung über das Fischgehirn. Cornell University (1868-1893) by some of Fragen aus der Morphologie des Vorderhirns Anatomischer Anzeiger 9:568-569. his former Students. Ithaca, N.Y.: Comstock der Cranioten. Vorläufige Mitteilung von F. K. Burckhardt R (1895a) Schlussbemerkung zu K.F. Publishing Co., pp. 259-314. Studnička in Prag (Mit 2 Tafeln). Anatomischer Studnička’s Mitteilungen über das Fischgehirn. Köppen, Max (1888) Zur Anatomie des Anzeiger 9:307-320. Anatomischer Anzeiger 10:207-208. Froschgehirns (Hierzu Taf. I-III). Archiv für Wiedersheim, Robert (1883) Lehrbuch der Burckhardt R (1895b) Der Bauplan Anatomie und Entwickelungsgeschichte (His – vergleichenden Anatomie der Wirbelthiere des Wirbelthiergehirns. Mit Tafel VIII. Braune; Anatomische Abtheilung des Archives auf Grundlage der Entwicklungsgeschichte Morphologische Arbeiten (Schwalbe) 4(2):131- für Anatomie und Physiologie, zugleich bearbeitet von Prof. Dr. Robert Wiedersheim. 150. Fortsetzung der Zeitschrift für Anatomie und Mit 607 Holzschnitten. Jena: Verlag von Gustav Burckhardt R (1907) Das Zentral-Nervensystem Entwickelungsgeschichte) Jahrgang 1888, pp. Fischer, xvi + 905pp. der Selachier als Grundlage für eine Phylogenie 1-34. Wilder, Burt Green (1875) Notes on the des Vertebratenhirns. I. Teil: Einleitung und Köppen, Max (1892) Beiträge zur American Ganoids. I. On the respiratory Scymnus lichia (Mit 5 Tafeln Nr. I-V und 64 vergleichenden Anatomie des actions of Amia and Lepidosteus. II. On the Textfiguren; Eingegangen bei der Akademie Centralnervensystems der Wirbelthiere. Zur transformations of the tail of Lepidosteus. am 13. Juni 1906.). Nova Acta Academiae Anatomie des Eidechsengehirns. Mit Tafel XXII- III. On the transformation of the pectoral Caesareae Leopoldino-Carolinae Germanicae XXIV. Morphologische Arbeiten (Schwalbe) fins of Lepidosteus. IV. On the brains of Amia, Naturae Curiosorum (= Abhandlungen der 1:496-515. Lepidosteus, Acipenser and Polyodon (3 Plates). Kaiserlichen Leopoldinisch-Carolinischen Meyer, Adolf (1892) Ueber das Vorderhirn American Association for the Advancement of Deutschen Akademie der Naturforscher). einiger Reptilien (Mit Tafel IV und V). Zeitschrift Science Proceedings 24:151-193. 73:241-450. für Wissenschaftliche Zoologie 55:63-133. Wilder, Burt Green (1876) Note on the development Edinger L (1892) Untersuchungen über die Nakagawa, Isaac (1891) The Origin of the and homologies of the anterior brain-mass with vergleichende Anatomie des Gehirns II. Das Cerebral Cortex and the Homologies of the sharks and skates (1 fig.). American Journal of Zwischenhirn, 1. Teil: Das Zwischenhirn der Optic Lobe Layers in the Lower Vertebrates (wit Science (Series 3) 12:103-105. Selachier und der Amphibien. Abhandlungen 1 Plate). Journal of Morphology 4(No. 1. – July, Wilder, Burt Green (1877) On the brain of der Senkenbergischen Naturforschernden 1890.):1-10. Chimaera monstrosa (1 plate). Proceedings Gesellschaft in Frankfurt a/M 18:3-55. Oyarzun, A. (1890) Ueber den feineren Bau des of the Academy of Natural Sciences of Edinger L (1896) Untersuchungen über die Vorderhirns der Amphibien (Hierzu Tafel XX Philadelphia 29:219-250. vergleichende Anatomie des Gehirns, III. Neue und XXI). Archiv für Mikroskopische Anatomie Wilder, Burt Green (1887) The dipnoan Studien über das Vorderhirn der Reptilien. 35:380-389. brain. (Abstract of a paper on the brain of Abhandlungen der Senkenbergischen Rabl-Rückhard, Hermann (1882) Zur Ceratodus, with remarks upon classification Naturforschernden Gesellschaft in Frankfurt Deutung und Entwickelung des Gehirns der and the general morphology of the vertebrate a/M 19:313-386. Knochenfische (Hierzu Taf. VI u. VII). Archiv brain, read by invitation before the National Edinger L (1899) Untersuchungen über die für Anatomie und Physiologie (Anatomische Academy of Sciences, April 22, 1887) (3 fig.). vergleichende Anatomie des Gehirns, 4. Abtheilung) Jahrgang 1882, pp. 111-138. American Naturalist 21:544-548. Studien über das Zwischenhirn der Reptilien.

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Abhandlungen der Senkenbergischen Nervensystem der Wirbeltiere. Zeitschrift für Newton Parker. With Additions by the Author Naturforschernden Gesellschaft in Frankfurt wissenschaftliche Zoologie 20:273-456. and Translator. Two hundred and seventy a/M 20:161-197. Stieda L (1870) Studien über das Centrale Woodcuts. London: Macmillan and Co., and Edinger L, Wallenberg A, Holmes GM (1903) Nervensystem der Wirbelthiere. Mit vier Tafeln. New York, xxvi + 345pp. Untersuchungen über die vergleichende Leipzig: Verlag von Wilhelm Engelmann, 1870, Wiedersheim Robert (1887) Zur Biologie von Anatomie des Gehirns, 5. Untersuchungen 468pp. (Separat-Abdruck aus der Zeitschrift für Protopterus (Mit 1 Abbildung). Anatomischer über das Vorderhirn der Vögel. Abhandlungen wiss. Zoologie, XX. Bd.). Anzeiger 2(23):707-713. der Senkenbergischen Naturforschernden Stieda L (1893) Ueber den Bau des Wiedersheim R (1890) Beiträge zur Gesellschaft in Frankfurt a/M 20:343-426. Zentralnervensystems der Amphibien und Entwicklungsgeschichte von Proteus Meyer A (1895) Zur Homologie der Reptilien. Leipzig: Engelmann. anguineus (Hierzu Tafel VI und VII). Archiv für Fornixcommissur und des Septum lucidum Studnička FK (1894) Eine Antwort auf die Mikroskopische Anatomie (Hertwig - la Valette bei den Reptilien und Säugern. Anatomischer Bemerkungen R. Burckhardt’s zu meiner St. George – Waldeyer) 35:121-141. Anzeiger 10:474-482. vorläufigen Mitteilung über das Vorderhirn der Wiedersheim R (1890) Beiträge zur Rabl-Rückhard H (1877/1878) Das Cranioten. Anatomischer Anzeiger 9(10):691- Entwicklungsgeschichte von Salamandra atra Centralnervensystem des Alligators. Zeitschrift 693. (Hierzu Tafel XIX). Archiv für Mikroskopische für wissenschaftliche Zoologie 30:336-373. Studnička FK (1895a) Bemerkungen zu dem Anatomie (Hertwig - la Valette St. George – Rabl-Rückhard H (1881) Ueber das Vorkommen Aufsatze: „Das Vorderhirn der Cranioten“ Waldeyer) 36:469-483. eines Fornixrudimentes bei Reptilien. von Rabl-Rückhard. Anatomischer Anzeiger Wilder BG (1876) Notes on the North American Zoologischer Anzeiger 4:281-284. 10:130-137. Ganoids, Amia, Lepidosteus, Acipenser, Rabl-Rückhard H (1887) Zur onto- und Studnička FK (1895b) Beiträge zur and Polyodon, with three Plates (From the phylogenetischen Entwickelung des Torus Anatomie und Entwickelungsgeschichte Proceedings of the American Association for longitudinalis im Mittelhirn der Knochenfische. des Vorderhirns der Cranioten. Erste the Advancement of Science, Detroit Meeting, Anatomischer Anzeiger 2(17):549-551. Mitteilung. Sitzungsberichte der Böhmischen August, 1875). Salem, Mass: Printed at The Rabl-Rückhard H (1894) Das Vorderhirn Gesellschaft der Wissenschaften, math.- Salem Press, 1876, 62pp. der Cranioten (Mit 16 Abb.). Anatomischer naturwissenschaftliche Klasse Wilder BG (1876) On the brains of fishes. Anzeiger 9:536-547. Studnička FK (1895c) Beiträge zur Proceedings of the Academy of Natural Rabl-Rückhard H (1895) Noch ein Wort an Anatomie und Entwickelungsgeschichte Sciences of Philadelphia 28:51-53. Herrn Studnička. Anatomischer Anzeiger des Vorderhirns der Cranioten. Zweite Wilder BG (1876) A brief account of the 10:240. Mitteilung. Sitzungsberichte der Böhmischen development and general structure of the Stieda L (1868) Studien über das centrale Gesellschaft der Wissenschaften, math.- brain (5 fig.). Ithaca, 7pp. Nervensystem der Vögel und Säugethiere (Mit naturwissenschaftliche Klasse Wilder BG (1876) On the brains of some fish- Tafel I-III)+. Zeitschrift für wissenschaftliche Wiedersheim R (1886) Elements of the like vertebrates. American Association for the Zoologie 19:1-94. Comparative Anatomy of Vertebrates. Adapted Advancement of Science Proceedings 25:257- Stieda L (1870) Studien über das centrale from the German of Robert Wiedersheim, by W. 259.

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SUPPLEMENT 1: TRANSCRIPTION OF THE ORIGINAL 1894 REPORT OF F. K. STUDNIČKA

The present report, originally entitled Zur Säugetiere, bekanntlich einem Riechcentrum, in den Hemisphären sich befindet. Meinen Geschichte des „Cortex cerebri“, was delivered homologisiren darf; man hat unter anderem Untersuchungen zufolge besitzt aber auch by F. K. Studnička in 1894, as a lecture on die directe Verbindung dieser Formation mit das Cyclostomengehirn eine mehr oder the 8. Meeting of the German Anatomical dem Bulbus olfactorius bewiesen. weniger deutlich ausgeprägte Hirnrinde in den Society held in Strassburg i. E., from 13. to Man war bis unlängst allgemein der Hemisphären. 16. May 1894 (during the Fifth Session of the Meinung, dass die Vorderhirnhemisphären Bevor wir von diesem Cortex reden meeting). It was subsequently published in der Amphibien einer Cortexformation ganz können, ist es nötig, zu fragen, was wir Transactions (Verhandlungen) of that meeting, entbehren, bis die Untersuchungen von eigentlich bei den Cyclostomen, speciell den in a supplement volume to the official journal NAKAGAVA (Journ. of Morph., 1891) uns Petromyzonten, bei welchen ursprünglichere of the society, the Anatomischer Anzeiger. gezeigt haben, dass bei einem Urodelen – bei Verhältnisse zu finden sind, als Hemisphären Spelerpes ruber nämlich – in der medianen betrachten sollen. Wie bekannt, existiren in Herr F. K. STUDNIČKA: Zur Partie des Hirnmantels kleine, von dem der Litteratur Geschichte des „Cortex cerebri“. centralen Hirngrau getrennte Gruppen von Ganglienzellen sich befinden, die uns eine (p. 195) Anatomischer Anzeiger, primitive Hirnrinde darstellen sollen. Auch zwei Deutungen des Petromyzontengehirns, Ergänzungsheft zum IX. Band (1894.): BURCKHARDT macht in einer seiner Arbeiten wenn man nicht von den älteren, z. B., der von Verhandlungen der Anatomischen (Ueber Protopterusgeh., 1892) die Bemerkung, JOH. MÜLLER reden will. Gesellschaft auf der achten dass sich bei Triton an einer kleinen Stelle des Nach der älteren, die z. B. von B. G. WILDER, Versammlung in Strassburg i. E., vom Palliums der Hemisphäre eine vielleicht dem besonders von AHLBORN und jetzt wieder 13.-16. Mai 1894., pp. 193-197. Ammonscortex der höheren Tiere homologe von S. P. GAGE und mir (Anat. Anz. Bd. 9, Hirnrinde befindet. Einzelne Zellen in den No. 10) vertreten wird, sind die Wände der (p. 193) äusseren Schichten des Amphibienpalliums Hemisphären, das Pallium inbegriffen, M. H.! Ich erlaube mir hier einige Worte über das bewies endlich noch OYARZUN (A. f. m. A., überall gleich dick, und der vordere Teil des erste Auftreten der sogenannten grauen Rinde 1890). sog. Ventriculus III ist oben zwischen den oder des „Cortex“ der Vorderhirn-Hemisphären Es ist sehr sonderbar, dass die Dipnoer, Hemisphären durch die Tela chorioidea und in der Reihe der Wirbeltiere mitzuteilen: speciell der Protopterus, dessen Gehirn im teils, vorn nämlich, durch den oberen Teil der Die graue Rinde des Säugetiergehirns Ganzen einfacher als das der Amphibien Lamina terminalis (Lam. supraneuroporica war schon den ältern Anatomen bekannt, gebaut ist, eine Hirnrinde in dem Pallium der BURCKHARDT’s z. Th.) gedeckt. diejenige der Vögel wurde dagegen erst von Hemisphären besitzen. Es war FULLIQUET Nach der zweiten Ansicht, die zuerst BUMM (1883) eingehender beschrieben. Dass (Recueil zool. suisse, 1886), der sie zuerst EDINGER in seinen „Untersuchungen über sich eine solche auch in dem Reptiliengehirn auf seinen Abbildungen gezeichnet hatte; das Vorderhirn“ ausgesprochen, und der sich befindet, darauf machte uns in seiner Arbeit detaillirter beschrieb sie in der letzten auch WIEDERSHEIM in seinem „Lehrbuche“ über das Zeit BURCKHARDT; er hat gezeigt, dass – angeschlossen hat, sind die „Hemisphären“ ganz ähnlich wie bei den Reptilien – auch nach der Bezeichnung der früheren Autoren (p. 194) hier der Ammonscortex von dem übrigen nur den Basalganglien (Corpora striata) Cheloniergehirn erst STIEDA (1875) Cortex der Hemisphären gesondert ist. Der der Amnioten homolog, die Tela stellt uns aufmerksam. Der Cortex der Reptilien, der Ammonscortex ist hier, wie man nach den dagegen das eigentliche Pallium eines ganz niedersten Amnioten, ist ziemlich interessant; Abbildungen BURCKHARDT’s schliessen kann, reducirten unpaaren Grosshirns dar. Das er wurde in der letzten Zeit von mehreren besser entwickelt und zellenreicher als der Petromyzontengehirn soll man nach diesen Autoren eingehender studirt, so von SCHULGIN, übrige Cortex der Hemisphären, der nur durch letzteren Autoren auf dieselbe Art auslegen, KÖPPEN, AD. MAYER und besonders von einzelne Gruppen von Ganglienzellen gebildet wie bekanntlich RABL-RÜCKHARD das EDINGER. Es wurde erkannt, dass man einen wird. Teleostiergehirn ausgelegt hat. grösseren Teil desselben an der medianen Die Dipnoer und die Amphibien wären Das Auftreten der grauen Hirnrinde der hinteren Partie der Hemisphären, gleich an dem also nach den bisherigen Kenntnissen die Hemisphären ist hauptsächlich auf das Pallium Fornix, mit dem bekannten Ammonscortex der niedersten Wirbeltiere, bei denen die Hirnrinde derselben beschränkt. Nach den Autoren,

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(p. 196) Die Untersuchungen von RETZIUS (Biol. ganze Cortex nur mit dem Ammonscortex die die zweite Auslegung vertreten, ist das Unters. V) haben uns gezeigt, dass bei Myxine anderer Tiere zu vergleichen ist, und wie Pallium nur epithelial entwickelt, infolgedessen alle Ventrikel des Vorderhirns bis auf kleine dieser ein Riechcentrum ist. Zu einem kann hier von einer Hirnrinde natürlich keine Spuren obliterirt sind. Ich habe nun beobachtet, Auftreten der übrigen Rindenformation, an Rede sein, nach den ersteren dagegen ist das dass in diesem massiven Vorderhirne, genau die sich vielleicht andere Functionen binden, Pallium massiv, und es wäre ganz möglich, an jenen Stellen, wo bei Petromyzon die wäre es hier also noch nicht gekommen. dass es auch in ihm zur Bildung eines Cortex bekannten Zellgruppen sich befanden, eine Es ist wahrscheinlich, dass hier die ganze kommen konnte. schön entwickelte Gehirnrinde Hemisphäre nur ein höheres Riechcentrum Nach meinen Untersuchungen besitzen darstellt. wirklich die Petromyzonten in diesem Teile des (p. 197), Für die Anschauung der Gehirnrinde der Gehirns kleine Gruppen von Ganglienzellen, die aus zwei, in der medianen Partie Cyclostomen als eines Riechcentrums spricht ganz denen ähnlich, wie sie zum Beispiel in dem der Hemisphäre aus drei Schichten von auch der Umstand, dass bei den sehenden Pallium von Protopterus oder Spelerpes sich Ganglienzellen gebildet ist, sich findet. Petromyzonten die Hemisphärenrinde weniger finden. Ich halte nun diese Zellengruppen für Es ist bekannt, dass überall in der Reihe der gut, bei der blinden Myxine, die einen stärker eine wirkliche, ganz primitive Hirnrinde. (Diese Wirbeltiere, wo in den Hemisphären eine graue entwickelten Riechapparat besitzt, auch die Zellengruppen sind nicht in allen untersuchten Hirnrinde sich befindet, vielleicht mit einziger Hirnrinde stärker entwickelt ist. Exemplaren gleich deutlich ausgeprägt, Ausnahme der Amphibien, der Ammonscortex Zum Schluss dieser kurzen Mitteilung erlaube manchmal liegen die Zellen nur zerstreut in der von dem übrigen getrennt ist, und dass er, ich mir noch zu bemerken, dass der Cortex der Hemisphärenwand). je niedriger in der Reihe der Wirbeltiere wir Petromyzonten bereits auf den Abbildungen Man könnte einwenden, dass es ganz herabsteigen, desto grösser im Verhältnisse zu in einem Werke von Mss. SUSANNE PHELPS möglich ist, dass auch unter der Oberfläche dem übrigen Cortex ist. GAGE 1), und der von Myxine (aber nur ganz eines Corpus striatum eine Hirnrinde sich Bei den Cyclostomen finden wir an den schematisch) auf zwei Abbildungen im 5. Bd. entwickeln könnte und nicht nur in dem Hemisphären, die, wie ich anderswo (im Anat. der „Biolog. Untersuchungen“ von RETZIUS Pallium, und dies wäre, so könnte man, die Anz. Bd. 9, No. 10) zu beweisen versuchte, gezeichnet ist, natürlich aber ohne als solcher zweite Ansicht anerkennend, meinen, um so nur der hintersten Partie der Hemisphären gedeutet zu werden. eher möglich, da doch das Corpus striatum höherer Wirbeltiere homolog sind, nur 1) The Brain of Diemyctylus viridescens. The auch die Function des rudimentären Palliums eine Art von Cortex. Ich erlaube mir nun WILDER Quart. Cent. Book, Ithaca NY. 1893 (Pl. übernehmen musste. Da natürlich kann nur das die Hypothese auszusprechen, dass dieser VIII, Fig. 105, 106.), Studium der Entwickelung und vergleichenden Anatomie des sog. „Corpus striatum“ entscheiden. Ich erlaube mir nur noch an dieser Stelle auf denjenigen Teil des Gehirns, der zwischen der Hemisphäre und der Tela, nach der anderen Deutung zwischen dem Corpus striatum und dem Pallium liegt, hinzuweisen (vergl. Figure 1). In diesem Teile, der doch schon zu dem Pallium gehören müsste, einen massiven Teil desselben darstellend – wenn die zweite Ansicht angenommen wäre – ist nämlich kein Cortex entwickelt. Wenn wir die erste Deutung anerkennen, müssen wir diesen Teil als den inneren Rand der Hemisphäre betrachten; er befindet sich hier auf derselben Stelle, wo anderswo (z. B. schon bei Reptilien) der Fornix zu finden ist. Ich glaube, dass dann jeder Zweifel, ob jene Zellgruppen im Petromyzontengehirne einen wirklichen Cortex darstellen, wegfällt, wenn wir dasselbe mit dem nahe verwandten Myxinehirn vergleichen. Figure 1. Ein Querschnitt durch die Hemisphären von Petromyzon Planeri.

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Discussion Hirn, bei welchen die Hirnrinde ganz anderer Riechstrahlung. An dem Gehirn von Petromyzon Function dient, zu sprechen. kann man solche Fasern nicht so leicht sehen, Herr BURCKHARDT ist derselben Ansicht, aber an Präparaten, die mit der GOLGI’schen dass die Vorderhirne niederer Fische fast (p. 198) Methode angefertigt wurden, konnte ich von ausschliesslich olfactorischer Function dienen, Herr STUDNIČKA: Ich habe wirklich an dem den Zellen des „Cortex“ einzelne gegen die sieht aber gerade darin das Hindernis, von Gehirn von Myxine zahlreiche Nervenfasern mediane Gegend des Gehirns auslaufende einer Homologie der Rinde im Vorderhirn der in den einzelnen Cortexschichten gesehen, Nervenfasern sehen. niederen Fische mit derjenigen im amphicölen die radiär verlaufen, - also vielleicht eine

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