Int..I. De\'. Bio!' 40: 69-75 (1996) 69
Alfred Kuhn, his work and his contribution to molecular biology
ALBRECHT EGELHAAF* Zoologisches Institut der Universitat K61n, K61n, Germany
Among the developmental biologists of this century Alfred evolution" (Kuhn 1959) were of great impact for Kuhn. Kuhn is an outstanding personality. Of greatest impact are his Weismann's research projects and objects laid the foundation for studies on the action of genes in development that maps him a his interests in developmental physiology. pioneer of the "one gene-one enzyme" hypothesis. This aspect After his promotion (1908) Kuhn became second assistant of will be in the center of the following report. However, it would be Weismann. Following his habilitation (1910) he worked as unjustified in view of his universality and broad influence not to "Privatdozent" and subsequently became "a.o. Professor" (asso- mention his other scientific interests comprising an astonishing ciate professor) at the Zoological Institute in Freiburg. Research variety of themes and objects. Much of this work can be traced periods in Naples and Heidelberg helped to enlarge his experi~ back to his early period of scientific activity in Freiburg. ences in a variety of projects. During World War I he was a med- Kuhn himself published only a short biographical account on ical orderly (1915-1918). The following two years he cooperated his scientific career until 1937 (Kuhn, 1959). He was born on with the famous embryologist Karl Heider at the Zoological April 22nd, 1885 in Baden Baden (South West Germany), Institute in Berlin. In 1920, Kuhn received the call to become full attended the gymnasium in Freiburg im Breisgau and began professor in Gbttingen. During the subsequent 17 years full of studies of science at the university there. activities he transformed the institute to a place for modern Of greatest influence were the both, Prof. August Weismann, research and teaching. In this time the foundations for his suc- zoologist and evolutionist, and the physiologist Johann von cess in genetics and developmental biology were laid. Gbttingen Kries. It was the latter who suggested investigations on sensory was a unique place at that time. The collaboration of outstanding physiology, e.g. on the function 01 the labyrinth of reptiles (Kuhn scientists and mathematicians and the stimulating mutual and Trendelenburg, 1908) and on statocysts of crustacea exchanges created the background for fruitful research. (Kuhn, 1914). Such studies culminated in a survey on "The spa- Especially successful was the collaboration with the botanist tial orientation of animals" (Kuhn, 1919) which contributed sig- Fritz von Wettstein (during the period 1925-1931). With him, nificantly to a classification of notions and a deeper understand- Kuhn shared many interests in research and teaching. It was ing of the underlying behavior. It directed the emerging unique at that time in Germany that lectures in the same topics "Verhaltensphysiologie" for many years. Kuhn also contributed (genetics, developmental biology) were given alternatively from innovative and important papers on color vision of insects (par~ two lecturers as fundamentals of a "General Biology". tially in collaboration with the physicist Pohl; Kuhn and Pohl, Increasing pressure of the NSDAP (Nazi.Party) after the 1921) and cephalopods. Last but not least we owe Kuhn the first "MachtObernahme" (Grossbach 1988) prompted Kuhn to leave "Manual of experiments in animal physiology" written by a zool- the University of Gbttingen. Just at that time the "Kaiser- ogist (Kuhn, 1917). Wilhelm-Gesellschaft" could offer him the position of a second Of deepest influence on the young student was August director of the "Kaiser-Wilhelm-Institut fur Biologie" at Berlin-
Weismann. His encyclopedic knowledge and u" the most serious Dahlem. He took over the position of Richard Goldschmidt who and lifelong dedication to a great problem, namely the formation emigrated in 1936 to the USA. This change enabled KUhn to of the theory which should solve the questions of inheritance and continue and intensify his research work.
*Address for reprints: Zoologisches !nstitut der Universihit K61n, Weyertal 119,0-50923 K61n, Germany. FAX: 221-4705171.
0214-62R2/96/$03.00 o lIBC Pre~\ f'nnted m Spain 70 A. [gel/waf
As a consequence of the war, the translocation of the institute problems. In Weismann's concept of heredity and the realization in 1943 to Hechingen (South West Germany) and the loss of of hereditary information the "Keimplasma" presented the conti- important coworkers reduced the scientific activities for a few nuity throughout the sequence of generations. In this context years. They could be reassumed only after the new "Max- Kuhn analyzed the development of reproductive cells Planck-Institut fur Biologie" in TObingen was created and ready ("Keimbahn") in parthenogenetic crustacea and the obviously for occupancy in 1951. In 1958 Kuhn retired from his position as determinative development of the embryo of Polyphemus. managing director but continued scientific research until shortly Another topic was his extensive research on Hydrozoa con- before his death on November 22nd, 1968. For five years (1945- ducted in the much appreciated Stazione Zoologica in Naples. 1950) he was also the head of the Zoological Institute at the Starting from studies on the branching patterns of developing University of TObingen. Hydroids It culminated in a voluminous presentation of the At that time he was once again engaged in teaching demon- ontogeny and the phylogenetic relationships among Hydrozoa strating his impressing talent as an academic teacher. His pre- (Kuhn, 1913). Cytological investigations on amoebae con- sentations were clear and impressive - always without manu- tributed to a deeper understanding of the interconnections script even in two hour lectures - vivid, meaningful and eloquent, between nuclear and cytoplasmatic division. until his old age. Better than any textbook could do, he Numerous and diverse contributions to animal morphology impressed his students with his carefully selected examples and followed well into the thirties. Among them were publications on his illustrations in form of large format lantern slides. the morphology of sensory and nematocyst organs in Hydrozoa Many honors were conferred to him: membership in several (Kuhn 1914-1016), the rudimentary "Morphologie der Tiere in domestic and foreign academies, scientific prizes and finally the Bildern" (2 volumes, Kuhn, 1921, 1926), and an article on highly selected award of the "Orden Pour Ie Merits der Hydrozoa in the "Handw6rterbuch der Naturwissenschaften" Friedensklasse fOr KOnste und Wissenschaften" in 1964. (Kuhn, 1932). These publications show Kuhn's talent for careful Of long lasting influence, first of all in the German speaking observation and artistic presentation. He himself in private talk scientific community, were the textbooks of Kuhn. They reflect spoke sometimes of being an "eye-minded person". He was fas- his universal spirit, his power as a lecturer who concentrated on cinated by studying the great diversity of animal forms and struc- the essential, but also his didactic and artistic gifts. His tures and their development in ontogeny and evolution. Again "Grundriss der allgemeinen Zoologie" (Basics of General and again they stimulated him to ask causal questions. Zoology) was published in numerous editions since 1922. This Weismann's experiments on temperature modifications of the book influenced generations of students in Biology and wing patterns of lepidoptera had a lasting influence on Kuhn's Medicine. Even the new edition revised by R. Wehner and W. subsequent activities. Weismann treated these modifications Gehring uses Kuhn's schematic drawings of the "Bauplane" of from the standpoint of an evolutionist. For example, he consid- animals. The several editions of his "Grundriss der ered the "winteriorm" of the dimorphic butterily Araschnia levana Vererbungslehre" (since 1934) enables one to follow over the as being the phylogenetic older one having evolved in the last decades the increasing knowledge in genetics to which he con- glacial period. Kuhn's approach was that of a developmental tributed to considerable extent. The last great book of Kuhn biologist: The modifications of the wing pattern caused by "Vorlesungen uber Entwicklungsphysiologie" (1955, 1965) is changing temperature offered him the opportunity for an experi- unique in the thoughtful analysis of the problems of develop- mental analysis of a relatively simple, two~dimensional color pat- mental biology. The basic questions of development, morpho- tern. In collaboration with Karl Henke, his coworker for many genesis, and differentiation are presented in this book in a years (who became his successor in G6ttingen) Kuhn pursued mastertul way, even if molecular biology has greatly deepened systematically the influence of external and genetic factors on our insight into the processes of development since then. Kuhn the wing development. For this purpose they used a carefully showed the way of future research when he wrote: "For the time selected species, the flour moth Ephestia kuehniella. (This moth being we can only describe the
1935). They were inspired by Sturtevant to periorm these exper- thesis and the deciphering of the genetic code denote further iments (Beadle, 1951). It was Sturtevant who formerly has found steps along this way. The work of Beadle, Tatum and Lederberg that in Vlv mosaics the eye of the v-half is colored like wildtype was honored in 1958 with the Nobel prize. and, therefore, that the V-gene is expressed non-autonomous The basic idea of a connection between genes and chemical (Sturtevant 1920, 1932). Caspari also knew these results. That substances or processes, however, has been expressed much Caspari's paper which was quoted by Beadle and Ephrussi but earlier (e.g. by Garrod, 1909; Gross, 1914; Onslow, 1923; not discussed in detail was of influence for their experiments can Goldschmidt, 1927; Haldane, 1938; quoted after Beadle 1946, at least be assumed (Harwood, 1993) . 1951) . But the direct and continuing tackling of the problem was During the next years both groups worked very efficiently. initiated by the experimental approach using the mutants of Between 1935 and 1941 Beadle and his coworkers published Ephestia and Drosophiia defective in pigment synthesis. over 30, Kuhn's group 22 papers in this field. Directed by the Undoubtedly Kuhn took the first decisive step. same concept and using similar methods they both demonstrat- Kuhn was always open-minded towards suggestions and pro- ed that the problem was ready for being solved. Eventually their posals of competent colleagues. Exceptionally productive was research diverged but the most important goal was to find the his collaboration with Adolf Butenandt, the later Nobel laureate. primary action of genes. Beadle and coworkers were able to It started in Gbttingen and was continued in Berlin-Dahlem and demonstrate that the substances dependent from the gene vand Tubingen and resulted in two main streams of research: en are products of subsequent gene activities and, thus, links of 1) Kynurenine and 3-hydroxy-kynurenine (Butenandt ef al., a chain (Beadle and Ephrussi, 1937). Furthermore they showed 1949) were found to be intermediates of ommochrome synthe- the homology of the respective genes with corresponding ones sis. Biochemists were attracted in particular by the analysis of of the wasp Habrobracon (Beadle ef al., 1938). In turn Becker this new class of pigments. Again Becker (1939, 1942) was the and Plagge (1937; Plagge and Becker, 1938) demonstrated the first who named and characterized ommochromes. Butenandt homology of the genes A:a' of Ephestia and V of Drosophila, and his coworkers were able to elucidate the constitution of sev- respectively. They concluded, therefore, that their gene products eral ommochromes and to characterize them as phenoxazones should be identical. (Butenandt, 1957). Valuable contributions on the biosynthesis Both groups continued the search for the chemical composi- and distribution of these pigments in the animal kingdom were tion of these gene products. Important steps in this approach supplied by Linzen (1967, 1974). It should be added that Becker were the isolation of active extracts from both objects (Becker (Kuhn and Becker, 1942) compared quantitatively the relation 1937; Khouvine and Ephrussi 1937), the modification of the diet between the amounts of added kynurenine and subsequently of Drosophila as a means for influencing the pigment formation, produced pigment. The proportionality of both substances defin- and the proof of a bacterial synthesis of the V-product (Tatum, itively abolished the gene-"hormone" concept and established 1939). kynurenine as ommochrome precursor. Cooperation with experienced biochemists (A. Butenandt and 2) The second line of research was likewise connected to E.L. Tatum respectively) culminated in the expected break- Butenandt's laboratory. Kuhn and his coworker Piepho studied through: Beadle and Tatum presented evidence for the V-sub- the pupal molt of Ephestia (and Calliphora). They found that stance being kynurenine, the derivative of tryptophan (1940, pupation can be inhibited when the anterior part is ligated before quoted after Harwood 1993) . But they had to recognize that in a critical period in the prepupa (Kuhn and Piepho, 1936). They the meantime Butenandt, Weidel and Becker (1940) had come concluded, that a trigger for metamorphosis must be released to the same result. It is not astonishing that such a race provoked from the anterior part. By carefully planned combinations of liga- irritations (Harwood, 1993) . Both groups acted at the research ture, extirpation, and transplantation important steps in the hor- front in pursuit of a highly actual problem. Besides, both groups monal control of the development of holometabolous insects were effectively supported by the Rockefeller Foundation in the could be achieved (Piepho, 1951). Becker and Plagge (1939; frame of a project initiated by Warren Weaver for promoting Becker, 1941) went on to extract and concentrate the hormone "physiological genetics". Kuhn (1959) remarked with gratitude for molting and pupation. This line of research was taken over by that he would not have been able to carry out his investigations Butenandt's institute and brought to a successful end with the in such a striking way without this support. isolation of ecdysone (Butenandt and Karlson, 1954) and the The efforts of both groups culminated in the influential con- elucidation of its structure (Karlson ef ai., 1965). This achieve- cept of the "one gene - one enzyme" hypothesis, as formulated ment and further investigations supported drastically the under- by Beadle and Tatum (1941): "Each gene controls the reproduc- standing of causal relationships in insect development and its tion, function, and specificity of a particular enzyme". Kuhn genetic control (Karlson, 1963). (1941) became not aware of this statement when he wrote simul- One may ask why Kuhn did not continue the research on taneously: "..with the genes a+= v+ enzymes are made available genetic control of pigment synthesis with the same intensity as which catalyze these processes". Beadle presented a more dif- previously. Two facts predominantly are responsible for that. ferentiated formulation because in the meantime he turned to a First of all the situation in the "Grossdeutsches Reich" deprived new object, the mold Neurospora crassa. The production and him of three of his most able collaborators.Caspari was forced isolation of numerous metabolic mutants gave him and his to emigrate in 1935. Via Turkey he arrived the USA in 1936 coworkers the possibility to verify manyfold the one gene-one where he acquired high reputation as one of the most prominent enzyme concept, even in its later extension "one gene-one pro- geneticists. Becker (killed in 1941) and Plagge (killed in 1943) tein" (Beadle 1946). Thereby the foundation of molecular biolo- were victims of the 2nd World War. Kuhn was profoundly gy was laid. The elucidation of DNA structure and protein syn- shocked be the loss of these highly gifted and hardly replaceable Alfred Kiihn 73
Omrnochromes Becker, Bulenandt. Schiedt. Biekert, Linzen et al. 1939 scqq.
ffDCo/or' b/;id( to red
,Cder, SI:Z~. amount, o{thcplg~nt. granule"
POLYPEPTIDE
TRANSIA TlON _ Hxrrone producing eell mRNA
PROCESSING - TRANSCRIPTION - >=a+= v) 3. Testis
«one gene - one enzynle » I (Beadle & Tatum 1941,KUhn19411 Fig. 2. On the left: diagrammatic representation of the "A"~gene-induced effects in different cell types of the larva and adult of Ephestia kiihniel/a (after Kuhn, Caspari and Plagge 1935; legends translated to English). The original legend (omitted here) means: 'Oiagramm of the action of the gene A upon the phenotype by means of the hormone after transplantation of A-tissue into an a!ahost. 1-5 Sites of pigmentation. 3-norm = Hormone produced by the action of the gene A and released into the hemolymph. PRA= Prrmary reaction depending on the gene A in the cytoplasm" In the center: tryptophan-ommochrome pathway with the interacting genes and enzymes. On the right: the corresponding primary steps according to recent knowledge collaborators. In addition, the prerequisites for scientific work in ful. Together with the chemist Viscontini they were able to Germany were severely impeded during the war and thereafter. demonstrate several pteridine mutants in Ephestia (as inter- The second reason can be seen in Kuhn's different way of mediates and eye pigments) and to isolate pterin mutants thinking. He considered the activity of the gene a+ not as an iso- (Kuhn 1956). Improved methods for analysis of the lated biochemical process but intercalated in the development of ommochrome pathway permitted the resumption of the earlier the object. His draft (Fig. 2) demonstrates this clearly. In parallel studies. For the first time in an insect an a+-dependent tryp- to the chemical events the structural correlates were investigat- tophan oxygenase which catalyzes kynurenine formation was ed histologically and embryologically. Kuhn's thoughts and his demonstrated in vitro (Kuhn and Egelhaaf, 1958). A thorough mode of exploration were concentrated on interwoven effects: study of the pleiotropic action of the a-locus in Ephestia based "How are the temporal sequence and spatial order of precisely on quantitative determinations of tryptophan metabolites and those conditions brought about which guarantee the proceeding enzyme activities in development (Egelhaaf, 1963) enlarged normal development?" Having the cell as reacting system in the previous view considerably. Additional work on the chemi- mind, he wrote: "Which developmental potentials comprise the cal composition of pigment granules and of the systems of >reaction norm< of the cell of a given species and which condi- transport and storage of tryptophan metabolites (Colin et al., tions realize them?" (Kuhn 1965). This more universal vision (in 1981; Colin and Hedemann, 1982; Colin, 1984) can be seen as comparison to the ones prevailing in the USA in the thirties; Kuhn's inheritage to scientists directly originating from his Harwood, 1993) does not exclude that solving a certain problem school or indirectly influenced by him (e.g. BOckmann and his can only be performed by the causal analysis of a clear-defined students, Leibenguth, Stratakis). question. It characterizes KOhn- in contrast to his older colleague Hans Kuhn's interest in biochemical genetics was revived in Spemann that he never lost the interest in his old topics in devel- Tubingen by the research on pterin mutants in Drosophila per- opmental biology and cytology and in his former objects (e,g, formed by his colleague and friend Ernst Hadorn. Their collab- Cladocera, Hydrozoa). He resumed some of his early investiga- oration, initiated in 1953, was highly stimulating and success- tions and asked several of his students to continue. Witnessing 74 A. Egfllllli(t the critical attention and strict conclusions with which he accom. BUTENANDT, A. (1967). Uber Ommochrome. eine Klasse natOrlicher Phenoxazon-Farbstoffe, Angew. Chemie 69: 16-23. panied the students' progress one cannot state that he frittered p, BUTENANDT, A. and KARLSON. (1964). Uber die Isolierung eines away his time. Needless to say that the wing pattern remained Metamorphose-Hermons der Insekten in kristalliner Form. Z. Naturforsch. 96: one of Kuhn's favorite objects until his advanced age. His analy- 389-391. sis of a mosaic-promoting mutant of Ephestia (KOhn, 1960) BUTENANDT, A., WEIDEL, W. and BECKER, E. (1940). Kynurenin als demonstrated again the cooperation of more or less independent Augenpigmentbildung auslbsendes Agens bei Insekten. Naturwissenschaffen component areas in pattern formation by new arguments. His 28: 63-64. former assistant Viktor Schwartz (1953) drew similar conclusions BUTENANDT, A., WEIDEL, W. and SCHLOSSBERGER, H, (1949). 3-0xy- when he analyzed several wing pattern mutants of the moth Kynurenin als cn+-abhangiges Glied im intermediaren Tryptophanstoffwechsel Z. Naturforsch 4b: 242-244 Plodia interpunctella. Thereafter the interest in this topic declined CASPARI, E. (1933). Uber die Wirkung eines pleiotropen Gens bei der Mehlmotte irrespective of its evident advantages. Just more recently it has Ephestia kuhniella Zeller. W. Raux Arch Entw.Mech Org. 130: 353-381. been revived (Nijhout, 1985) by new concepts. COLLN, K., HEDEMANN, R. and OJIJO, E, (1981). A method for the isolation of At the center of KOhn's interest, however, remained the prob- ammochrome-containing granules from insect eyes. Experientia 37: 44-46. lems of "gene physiology". He followed the rapid development of COLLN, K. and HEDEMANN, E. (1982). Temporal storage of kynurenine and 3- molecular biology with great attention and was deeply impressed OH-kynurenine in the fat body of metamorphosing Ephestia kUhniella. by its progress. When comparing the new possibilities and Experientia 38: 1327-1329. insights with his own former attempts repeatedly the passion of COLLN. K, (1984). Spezifischer Transport von Metaboliten des L-Tryptophans in the experimenter broke through, so when he aimed: "Well, now die wachsende Oocyte: eine Grundlage mOtterlicher Pradeterminalion der Ommochrombildung bei der Mehlmotte. Verh. Dtsch Zool. Ges. 177: 148. one should do.. !". But never he overlooked the contemporary EGELHAAF, A. (1963). Uber das Wirkungsmuster des a-Locus von Ephestia kuh- limitations and the still unsolved great questions. They still relat. niella. Z. Vererbungsl. 94: 349-384. ed to morphogenesis and to coordination of developmental GROSSBACH, U. (1988). Der Weg zur allgemeinen Biologie: Entwicklungsphysio- events in complex, multicellular organisms. But this critical logie und Genetik in G6ttingen, G6ttinger Universilatsschriff., Ser, A: 85-97. insight could never discourage him, as he wrote (1965): "The HARWOOD, J, (1993) Styles in Scientific Thought. University Chicago Press, facts already known are everyone's possession; at the frontier to Chicago, London. the unknown lies the tempting zone of the research". KARLSON. P. (1963) Chemie und Biochemie der tnsektenhormone. Angew. Chemie 76: 257-265. Acknowledgments KARLSON, P., HOFFMEISTER, H., HUMMEl. H., HOCKS, P. and SPITIELER, G I thank Prof. G. Czihak and Prof. H.J. Rheinberger, University of (1965). Zur Chemie des Ecdysons. VI. Reaktionen des Ecdysonmolekuls Salzburg. for many valuable suggestions and assistance in translating Chem. Berichte 98: 2394-2402. the manuscr(Dt. KAY,L. (1989). Selling pure science in wartime: the biochemical genetics of G.w. Beadle. J History BioI. 22: 73-101 Selected References KHOUVINE, Y. and EPHRUSSI, B. (1937). Fractionnement des substances qui interviennent dans la pigmentation des yeux de Drosophila melanogaster. C.R. Soc. BioI. Paris 124: 885-887. BEADLE. G.w. (1946). The gene and biochemistry. In Currents in Biochemical Enlwicklungsgeschichle und Verwandtschaftsbeziehungen der Research (ed. D.E, Green). Interscience Publishers, New York. pp. 1-12. KUHN, A. (1913). Hydrozoen. Erg. Fortschr. Zool. 4: 1-284. BEADLE, G.w. (1951), Chemical genetics. In Genetics in the 20th Century (Ed. l.C. Dunn). Macmillan Comp., New York. pp. 222-239. KUHN, A. (1914). Versuche Uber die reflektorische Erhaltung des Gleichgewichts bei Krebsen. Verh Disch. Zool. Ges. 1914: 262-277 BEADLE, G.W., ANDERSON, R.l. and MAXWELL, J. (1938). A comparison of the diffusible substances concerned with eye color development in Drosophila. KUHN, A. (1933). Goethe und die Naturtorschung. Nachr. Ges. Wissensch. Ephesria and Habrobracon. Proc. NaN. Acad. Sci. USA 24: 80-85. G6ttingen 1933: 1-23. BEADLE, G.w. and EPHRUSSt, B (1935). Transplantation in Drosophila. Proc. KUHN. A. (1941). Uber eine Gen-Wirkkette der Pigmentbildung bei Insekten. Nat!. Acad. Sci. USA 21: 642-646. Nachr. Akad. Wiss. Gr5ttingen, Math-Physik. Klasse 1941: 231-261. BEADLE, G.W. and EPHRUSSI, B. (1937). Development of eye colors in KUHN.A. (1948). Biologie der Romantik. In Romantik, Rainer Wunderlich Verlag Drosophila: diffusible substances and their interrelations. Genetics 22: 76- Hermann leins, TObingen, Stuttgart, pp. 215-234. 86. KUHN, A, (1956). Versuche zur EntwicklunQ eines Modells der Genwirkungen. BEADLE, G,w. and TATUM, E.l. (1941), Genetic control of biochemical reactions Naturwissenschaften 2: 25-28. in Neurospora. Proc. Nat!. Acad, Sci. USA 27: 499-506. KUHN, A. (1960). Genetisch bedingte Mosaikbildungen bei Ephestia kuhniella. Z. BECKER, E. (1937). Extraktion des bei der Mehlmolte Ephestia kuhhniella die dun- Vererbungslehre 91: 1-26 kle Ausfarbung der Augen ausl6senden Gen-A-Hormans. Naturwissenschaften KUHN, A. and BECKER, E. (1942). Quantitative Beziehungen zwischen zugefOhr- 25: 507. tem Kynurenin und Augenpigment bei Ephestia kuhniella Z. Bioi. Zbl. 62. 303- BECKER, E. (1939). Uber die Natur des Augenpigments von Ephestia kuhhniella 317. und seinen Vergleich mit den Augenpigmenten anderer Insekten, Bioi. Zbl. 59: KUHN, A. CASPARI, E. and PLAGGE, E. (1935). Uber hormonale Genwirkungen 597-627. bei Ephestia kuhniella Z. Nachr. Ges. Wiss. G6ttingen, Math.-Physik. Klasse 2: BECKER, E. (1941). Uber Versuche zur Anreicherung und physiologischen Cha- 1-29. rakterisierung des Wirkstoffs der Puparisierung. BioI. Zbl 61: 360-388. KUHN, A. and EGELHAAF, A. (1958). The action of the mutation a in Ephestia kuh- BECKER, E. (1942). Uber Eigenschaften. Verbreitung und die genetisch-ent- niella on the formation of kynurenin from tryptophan. Proc. X. Int. Gongr. wicklungsphysiologische Bedeutung der Pigmente der Ommatin-Ommingruppe Genetics 2: 152. (Ommochrome) bei den Arthropoden. z. Vererbungslehre 80: 157-204. KUHN, A, and HENKE, K. (1929-1934). Genetische und entwicklungsphysiologi. BECKER, E. and PLAGGE, E. (1937). Vergleich der die Augenausfarbung bedin- sche Untersuchungen an der Mehlmotte Ephestia kuhniella Zeller. Abh. Ges. genden Gen-Wirkstaffe von Ephestia und Drosophila. Naturwissenschaften 25. Wiss. Gottingen, Math-Physik. Klasse IS, I-VII: 1929, VIII-XI/:1932, XIII-XI V: 809. 1934. BECKER, E. and PLAGGE, E. (1939). Uber das die Pupariumbildung ausl6sende KUHN, A. and PIEPHO, H. (1936). Uber hormonale Wirkungen bei der Verpuppung der Hormon der Fliegen. BioI. Zbl. 59: 326-341. Schmellerlinge. Nachr. Ges. Wiss. Gottingen, Math -Physik. Klasse 2: 141-154. Alfred Kiih" 75
KUHN. A. and POHL. R. (1921) . Dressurlahigkeit der Bienen auf Spektrallinien. KUHN, A (1921, 1926). Morphologie der Tiere in Bildern. 1. Heft: Flagelfaten, NatUlWissenchaften 9: 738-740. 2.Heft: Rhizopoden. Verlag Gebruder Bornlraeger, Berlin. KUHN. A. and TRENDELENBURG. W. (1908). Vergleichende Untersuchungen KUHNA (1922). Grundri{3 der allgemeinen Zoologie (17th edition 1969). Georg des Ohrlabyrinths der Reptilien Arch. Ana!. Physiol. Physiol. Abt.: 160-185 Thieme Verlag, leipzig, Stuttgart. LlNZEN. B. (1967). Zur Biochemie der Ommochrome. Unterteilung. Vorkommen KUHN, A. (1932). Coelenterata. In Handw6rterbuch der NatulWissenschaflen. und physiologische Zusammenhange. NatulWissenchaften 64: 259-267. Verlag Gustav Fischer. Jena, pp. 740.774. LlNZEN. B. (1974). The tryptophan.ommochrome pathway in insects. Adv. Insect KUHN, A (1932). Allgemeine Zoologie. In Lehrbuch der Zoologie (Eds. C. Claus. Physiol. 10: 117-246. K. Grobben, A. Kuihn). J. Springer Verlag. Berlin, Wien. NIJHOUT, H.F. (1985) . The developmental physiology of color patterns in lepi- KUHN, A (1934). Grundriss der Vererbungslehre. QueUe & Meyer Verlag, doptera. Adv. Insect Physiol. 18: 181-247. Heidelberg (8th ed. 1984, revised by 0. Hess) NUSSLEIN-VOLHARD, C. and WIESCHAUS. E. (1980). Mutants affecting seg- KUHN.A (1950). Anton Dohrn und die Zoologie seiner Zeit. Pubblicazioni delia ment number and polarity in Drosophila. Nature 287: 795-801. stazione zoologica di Napoli, Suppl., Naples PIEPHO, H. (1951) . Uber die Lenkung der Insektenmetamorphose durch Hor- KUHN. A. (1955,1965). Vorlesungen uber Entwicklungsphysiologie J, Springer mone. Verh. Dtsch Zool. Ges. 1951: 62-76. Verlag, Berlin. Heidelberg. New York, PLAGGE, E. and BECKER. E. (1938). Die Ubereinstimmung der genbedingten AUgenausfarbungs-Wirkstoffe von Ephestia und Drosophila. Bioi. ZbI. 58: 231-242 Biographical memories and obituaries SCHWARTZ, V. (1953). Zur Phanogenese der Flugelzeichnung von Plodia inter- punctella. Z Vererbungslehre 885: 51-96. STURTEVANT, A.H. (1920). The vermilion gene and gynandromorphism. Proc BUTENANDT, A. (1968/69), Gedenkworte fur Alfred Kuhn, Orden Pour Ie Merite fUr Soc. Exp. Bioi. Med. 51: 325-327. Wissenschaften und Kuns/e, Reden und Gedenkworte 9: 125-130, STURTEVANT AH. (1932). The use of mosaics in the study of the developmental EGELHAAF, A. (1969). Auf dem Weg zur molekularen Biologie Alfred Kuhn zum effects of genes. Proc. VI. Int. Gong. Genetics 1: 304-307. Gedenken, NatulWissenchaften 56: 229-232, TATUM. E.L. (1939). Development of eye colors in Drosophila' bacterial synthesis GRASSE, G. (Ed.) (1972), Alfred Kuhn zum Gedachtnis, 5, Biologisches of V".hormone. Proc. Nat!. Acad. Sci. USA 26: 486-490 Jahresheft. Verb, Deutscher Biologen, Iserlohn, HENKE, K, (1955) , Forschung und Lehre heute, Zum 70, Geburtstag von Alfred Kuhn am 22. April 1955, NatulWissenchaften 42: 193-199, Books by A. Kuhn KOEHLER, 0, (1965), Alfred Kuhn zum 80, Geburtslag, NatulWiss, Rundschau 18. 493-496, KUHN, A. (1914-1916). Sinnesorgane und Nesselorgane der Hydrozoen. In Bronn KUHN, A (1959), Alfred Kuhn, Autobiographisches, Nova Acta Leopoldina 21: 's Klassen und Ordnungen des Tierreichs 2, 2. Abt. (Ed. H.G. Bronn). 274-280, Winter'sche Verlagshandlung. leipzig, pp. 370-538 RISLER, H, (1969), Alfred Kuhn zum Gedachtnis, Attempto (Nachrichten der KUHN, A. (1917). Anleitung zu tierphysiologischen Grundversuchen. Quelle & Freunde der Universitiif Tiibingen) 31/32: 89-91 Meyer Verlag. leipzig. SCHWARTZ, V, (1965). A Kuhn zum 22, April 1965, Z Naturforsch. 2Gb: 278- KUHN, A. (1919). Die Orientierung der Tiere im Raum. Gustav Fischer Verlag, Jena. 280