fifay 15, 1884] NATURE

the position of some of the Cretaceous deposits and the marked Piedmont. By t heir means great piles of broken rock must h~ve mineral differences between these and the Jurassic seem to indi• been transported into the lowlands ; hut did they greatly modify cate disturbances dnring some part of the ;-.:- eocomian, but I am the peaks, deepen the v:1lleys, or excavate the lake basms ? My not aware of any marked trace of these over the central and reply would be, '' T o no very material extent. " I r egard (he western areas. The mountain-making of th e existing Alps elates o-Jacier as the fil e rather than as the clusel of nature. The Alpme from the later part of the Eocene. Beds of about the age of our Jakes appear to be more easily explained-as the Dead Sea can Bracklesham series now cap such summits as the Diablerets, or only be explained-as the result of subsidence along zones r<;mghly help to form the mountain masses near the T iid i, rising in the parallel with the Alpine ranges, athwart the general d1 rectt0ns of Bifertenstock to a height of rr, 300 feet above the sea. Still valleys which already existed and had been in the main com• there are signs that the sea was then shallowing a nd the epoch pleted in pre-Glacial times. To produce these lake basins we of earth movements commencing. The Eocene deposits of Swit• should require earth movements o n n o greater scale t han have cerlancl include terrestrial and fluviatile as well as marine taken place in our own country since the furthermost extension remains. Beds of conglomerate occur, and even erratics of a of the ice·-fields. This opinion as to the origin of the lakes is, I granite from an unknown locality, of such a size as to suggest the believe, generally held to be a heresy, but it is a heresy which aid of ice for their transport. F or the present I prefer, for sake has been ingrained in me by some twenty years of study of the ofsimplicity, to speak of the upraising of the Alps as though it physiography of the Alps. were the result of a few acts of compression, though I am by no means s ure that this is the case. Thus speaking we find that in Miocene times a great mountain chain existed which covered R E CEN T MORPHOLOGICAL SPECULATIONS nearly the same ground as the present Alpine region of Mesozoic and crystalline rocks. To the north, and probably to the south, I.-On Alternation of Generations lay shallow seas, between which and the gates of the hills was J T. is more than sixty years sine~ C;h_amisso pointed out th~t a level tract traversed by rivers, ·perhaps in part occupied by m Salpa a solitary asexual md1v1dual produced a cham lakes. Over this zone, as it slowly subsided-in corrcspornl• of sexual individuals by budding, the viviparous eggs in these ence, probably, with the uplifting o f the mountain larnl-were becoming in turn the s olitary form. This he made his type of deposited the pebble beds of the nagelflue and the sandstones of Alternation of Generations. the molasse. Since his time the definition of this peculiar method of repro· Then came another contraction of the earth's crust ; the solid duction has been n arrowed, and the alternation of a series of mountain core was no doubt compressed, uplifted, and thrust individuals developed from an unfertiliscd egg, i.e. partheno· over newer beds, but the region of the softer border land, at any genetically, and one or more generations of sexually produced rate on the north, was apparently more affected, and the sub young is now called heterogamy; the term metal?enesis has been a lpine district of Switzerlarnl was the result. I may here call inventecl for cases of alternation of sexual and gemmiparous your attention to the fact that, whether as a consequence of this generations. or of subsequent movements, the Miocene heel s occur on the F ew instances can be cited where the slndy of a single genus northern flank of the Alps at a much greater height above the has brought out so many points of interest as in the case of the sea than on the southern, and haYc been much more upraised in pelagic Ascidian, Salpa. Two points in the history of this animal the central than in the western and eastern Alps. Further, still involved in controversy are the first phenomena of embryonic between the Lago Maggiore and the south of Saluzzo, Mesozoic development, and the mutual relationship of the two forms, the rocks are almost absent from the southern fl ank of the Alps, solitary individual and the colony that swim united in a chain. and the Miocene beds are but slightly exposed and occupy a A s regards the former matter, the fate of the egg and the comparatively lowland country. I think it therefore probable origin of the nutritive s tructure known as the placenta present that the second set of movements proclucecl more effect on the great difficulties. German than on the Italian side of the Alps, producing on the While vV. K. Brooks (Bull. ~f· /1,fuseum of Comp. Zoo!., latter a relative depression. In support of this we may remark H arvard University, iii.) believecl that the egg undergoes a that the rivers which flow from the Alps towards the north or regular segmentation resulting in the formation of a gastrula, the the west, start, as a rule, very far back, so that the watershed cavity of which is divided by a transverse constriction into two of the Alps is the crest of the t hird range reckoning from the chambers, one becoming the "placenta," Todaro (Atti delta R. north, and the great flat basin of the Po is the receptacle for a Accad. dei Lined, Rome, 1875, 1880), on the other hand, stated series of comparatiYely short mountain riYe rs. These also take that the solitary Salpa is the result, not of the division of the a fairly straight course to the gates of the hills, while the others true ovum, but of the follicular cells inclosing it, and that change not seldom from the lines of outcrop to the lines of clip during development, which takes place in a special part of the of the strata- a fact I think not without signifi ca nce. To this oviduct, the so-called uterns, a fold of the uterine wall forms a rule the valley of the Adige in the eastern region i s a n exception. decidua reflexa comparable to that of mammals. May not this be due to the remarkable series of mi.nor flcxures Salensky (Zoo!. Anzeiger, 1881; Mittheil. d. 200!. Stat. zu indicated by the strike of the rocks (l\fesozoic and earlier) N eapel, Bel. iv.) accounts for some of these conflicting statements immediately to the west of it, which probably influences the by showing that great variety exists in nearly allied species, but course of the Adda, and can, I think, be traced at intervals he also declares that previous observations were often inaccurate. along the chain as far as D auphine? Be this as it may, it is H e s tates that the fertilised ovum divides but slowly, and only obvious that the generally unifo rm cast-north-east to west-south• till the number of its segments reaches sixteen; and that probably west strike o f the rocks which compass the Alpine chain is it then entirely disappears, the tissues of the embryo being materially modifi ed as we proceed south of the Lake of Geneva, formed from a varying number offollicula,· cells. In some cases, changing rapidly in the neighbourhood of Grenoble from a as S. bicaudata, the so-called" clecidua" is not represented. To strike north-east to south-west, to one from north-west lo south• this most exceptional method of development he gives the. name e:ist. This subject, however, is too complicated to be followed of " follicular budding." further on the present occasion. I will only add that the singular Now the theory that Salpa is an instance of the alternation of trough-like upland valleys forming the upper parts of some of sexual and gemmiparons generations (i.e. of metagenesis), which \he best-known road passes- as, for instance, the Maloya-which was put forward by Chamisso and supported by the researches descend so gently to the north, and are cut off so abruptly on of K rohn, has been attacked hy Brooks, who believes that the the south, seem to me most readily explained as the remnants of so litary Salpa (which he calls the nurse) is hermaphrodite, and a comparatively disused drainage system of the Alps. gives rise by budding to a chain of males into each of which an It remains only to say a few words on the post-T ertiary history egg migrates from the nurse. This view of course supposes that of the Alps. vVe enter here upon a troubled sea of contro• the solitary and chain forms belong to the same generation, they versy, upon which more than the time during which I have being, in fact, respectively the sexu ally and asexually produced spoken might easily be spent ; so you will perhaps a llow me to offspring of one arnl the same solitary hermaphrodite Salpa. conclude with a simple expression of my own opinion, without T odaro, on the other hand, states that, in the solitary adult, entering into the arguments. That the glaciers of the Alps were certain of the follicular cells surrounding the ovum give rise. to once vastly greater than at the present time is beyond all dispute ; no organs, but remain as cell-masses ; and that from these the they covered the fertile lowlands of Switzerland, they welled up I stolon is eventually developed. Hence the chain-Salp:ce are against the flanks of the Jura aboYe N eufchatel, they crept over developed parthenogenetically, and the nurse is an older sexless ·the orange gardens of Sirmio, and projected into the plains of form, s erving to nourish the sexually complete chain.

© 1884 Nature Publishing Group 68 NATURE [May 15, 1884 ------,,------In Brooks' theory the main point is the migration of Ct:Enurus cerebra/is, Ttruia c,hfllOepidermis ; b, the pharyngeal cavity continuous with the second generation of Reclire) with true sexual reproduction there pericardium ; and c, two "club-shaped masses" of cells which is in addition a true alternation of generations" (Balfour, "Com• lie on either side of b, and which soon resolve themselves into parative Embryology, " vol. i. pp. 172, 173). Grobben (/oc. cit.), two lines of ova, one of which passes into the sinus system of however, has lately stated that the Cercaria:- are developed not each zooid. The discovery of undoubted ova in the s tolon when from a mass of cells produced by internal budding in the Redia the organs of the zooids are hardly indicated suggests, says but from an ovum developed parthenogenetically. This would Brooks, a migration from the nurse, which is therefore female. place these phenomena under the category of heterogamy. Now we have, in direct opposition to this, an observation of_ Among the Polychrdes there exist in Syllis, Myrianida, Salensky's, that in some cases a second ovary is developed in the and Autolytus undoubted cases of alternation of generations ; chain-Salpre ; and an indirect negation is entailed in the facts of but these are not of recent discovery, having been described by gemmation in Pyrosoma, which is generally allowed to be a less Qnatrefages, Krohn, anrl A. Agassiz about 1850-186o (Balfour, modified form. H ere we find the bud, when merely a protu• ibid., i. pp. 283, 284). berance on the mother, consisting of an epidermis derived from A general comparison of the various ways in which r eproduc• that of the mother, an " aTchenteric" cavity continuous with the tion is carried on within the limits of alternation of generations endostyle, and a mass of cells which are derived directly from the may be easily made by a series of diagrams in which A represents '' generative blastema." In this mass a single ovum can be seen the asexnal individual developed from the fertilised egg, B the quite as early relatively as in Salpa, and a second near the base sexual zooid, and AB those form s which carry on both methods supplies the secondary bud. Among the Composite Ascidians of reproduction. the case i s similar ; in Amourcecium the buds a re cut off from Pyroso111,1 a11d the post-abdomen and consist of outer tunic, mesentery (that is, Salpa Synascid;·a Dolio/um continuation of pharynx backwards), and two lateral masses in A solitary ? partheno- A cyatho7.<)oi plants. A A A A In Pyrosoma, the individual developed directly from the egg is Jieterogamy, which is not so common as metagenesis, has been the "cyathozooid," and this remains rudimentary, giving rise to the subject of very interesting memoirs by Adler and Lichten• the first four ordinary individuals by budding. There is here an stein. In a paper, "Ueher den Generationswechsel der Eichent alternation of a single asexual form with numerous generations Gallwespen" (Jenaische Zeitschrift, 1881), we have the result of produced by budding, each of which becomes hermaphrodite. Dr. Adler's work on "Gall-making Hymenopterous Insects," According to Ganin, we have a precisely simil ar case in the formerly described as belonging to eight different genera, namely Composite Ascidians, for he states that sexual organs only develop 1\'euroterus, Aphilothrix, Dryopha11ta, Biorhiza, Spathegaster, in the individuals produced by gemmation. Andricus, Teras, and Trigonaspis. H e confirms the conclusions In Doliolum the ovum, as before, gives rise to an asexual indi• of Lichtenstein that cer1 ain species of the first four of these vidual, but the lateral and median buds which arise on its dorsal genera are stages in the life-history of certain species of the last stolon do not b ecome sexually mature, The former only serve four. to nourish and protect the latter (Grobben, Arbeit, der Zool. ln• The gall wasps which in Ap,~l leave the small round scale-like sli'. zu Wien, iv.), from which a ventral stolon (stalk of attach• galls on the under surface of the leaves of the oak, have been de• ment) grows out, bearing sexual individuals. scribed as N euro/ents ventriculai-is; but the parthenogenetic egg Outside the group of the Tunicata, true alternation of genera• develops within a round soft "currant-gall ' to a wasp named tion occurs in some Ccelenterates, some Annelids, some Cestodes, Spathe,_f,zster baccarum. The latter escapes in June, and differs and possibly in the Trematodes. from the N euroterus in size, colour of the legs, and in the female The alternation of hydroid and medusoid forms in many in the number of joints in the antenn~. The eggs produced by Hydromedusre (Gymnoblastic and Calyptoblastic Hydroids and the Spathegaster when fertilised develop within N euroterus galls. Hydrocoralla), all Acraspeda except Pelagia, and possibly Fungia A still greater difference exists between the two generations among the Actinozoa, has been dwelt on in a previous paper in formerly called Biorhiza ren u m and Trigonaspis crustalis. this journal by Prof. Moseley, and little range o f modification Trigonaspis is 4 mm. long, winged, almost entirely black, with occurs except in the extent of development of the medusre. antennre of 15 ( o) and 14 ( 't) joints, while the Biorhiza is In Cestodes the complicated metamorphosis has been mistaken I ·5 mm. long, wingless, red-brown, and with 13 joints in the for metagenesis, but it is only in those cases where the cystic antennre ; the two forms live, moreover, in different kinds of worm develops a number of "heads" by gemmation, e.g. gall s. In all these cases the alternation is direct. BL1t among

© 1884 Nature Publishing Group May 15, 1884 l NATURE

other insects several generations produced by parthenogenesis 1 This is, however, in no way more strange than the transmission intervene between true sexual generations. of sexual characters. The typical case is that of the Aphiclcs, which has been long While, however, the case of the Tunicates may be considered known ; here there is little difference of habit or structure except doubtful, it will probably not be denied by unprejudiced ob• as regards wings, and possibly the generative organs. servers that the phenomena seen in the Insecta are more easily Some of the Aphicles, however, do show modifications in their accounted for by Leuckart's hypothesis than by Salensky's. life-history almost as remarkable as in the case of the Cynipidce It would seem that there could be no ground for saying with mentioned above. Lichtenstein's researches, though vigorously regard to the Gynipidce, that in a group of which it is charac• attacked by some French writers, have been confirmed by Kessler teristic that only the mature forms, and sometimes not even those, and Horvath. He observed that the Aphicles, living during are winged-one winged form is_ the larva_! condition of _a~other summer at the roots of various grasses, become winged in autumn which is smaller, but not otherwise very different, yet this 1s the and fly to the trunks of trees, where they produce sexual indi• case in Dryophanta scutellaris-Spathegaster taschenbergi. viduals ; the solitary egg of the female remains dormant in her It is probable, then, that these methods of reproduction have dried body till the following spring, when it develops into a not had in all cases the same origin, and, as in several other gall-making aphis, the foundress pseudogyne. This produces instances to which attention has been paid during the last few viviparous winged young (emigrant pseudogynes), which in June years, the resemblances, which occur in various animals in no fly back to the grass, lose their wings, and produce fresh genera• way connected but distribute~ over almost the ~hole a~imal tions by parthenogenetic eggs. This completes the cycle, and the kingdom, may best be considered as homoplastic, that 1s as generations distinguished by habitat are often different in appear• brought about in different ways under the influence of similar ance, even a large number of different forms being sometimes conditions of life. R. N. G. thus connected. For instance- Phylloxera quercus (Balbiani) migrates from Quercus ilex to Q. sessilijlora. THE PARIS ACADEMY OF SCIENCES P. vastatrix, from the leaf-galls to the root of the vine. THE yearly public meeting of this body was held on Monday, Tetraneura rubra, from galls on trunk of elm to roots of clog's May 5, under the presidency of M. Emile Blanchard. The grass. proceedings consisted mainly of a detailed statement of the awards T. ulmi, from elm-galls to roots of maize. made for prize essays or distinguished services rendered during Other less perfect examples of heterogamy, such as Cecido• the year 1883 to the various branches of the mathematical and myia and Ascaris nigrovenosa, are well known. natural sciences, useful arts, and industries. The current views concerning the probable origin of the phe• In Mechanics the Extraordinary Prize of 6000 francs, established nomena of heterogamy and metagenesis may be roughly classed to encourage improvements of all sorts in the efficiency of the in two groups, one formulated by Leuckart and supported by French Naval Service was divided, as in previous years, amongst Claus and Balfour, the other held by Salensky and Brooks. several candidates. For his "Studies on Marine Engines," now Leuckart supposed that alternation of generations is a division in course of publication, M. Taurines received 3000 francs, M. of labour in regard to reproduction in which the two chief kinds Germain 2000, for his "Treatise on Hydrography," and Capt. of multiplication, sexual and asexual, are divided between dif• A. de Magnac rooo, for his "New Astronomic N aviga• ferent individuals and generations. tion," published in 1877. The Montyon Prize, in the same de• The other theory is that these phenomena are due to a modifi• partment, was also divided, half going to M. Leon Francq, for cation of metamorphosis, Salensky also stating that "the con• his improvements in Lamm's steam traction engine, and half to nection between metagenesis and metamorphosis is much more Capt. L. Renouf, inventor of an instrument intended to simplify easily seen in Tunicates than in other animals." the observation of altitudes at sea, dispensing with the necessity If in an animal undergoing a metamorphosis the larva ac• of employing artificial horizons and enabling exact calculations quired the power of producing other individuals by budding, we to be made without stopping the vessel under sail or steam. M. should have the larval form undergoing finally a change into J acqucmier, inventor of the kinemometer, dynamometer, and the adult sexual form. At the same time it is obvious that this other useful appliances, gained the Plumey Prize ; and M. Marcel is not an indispensable condition ; fof the more individuals the Deprez the Fourneyron, for his ingenious electric experiments on larva produced the more incapacitated it would be for future the Chemin-de-fer du Nord. sexual reproduction, so that in all probability there would soon The Lalande Prize, founded by the illustrious astronomer to be no development beyond the larval stage. W. K. Brooks, in stimulate astronomical studies in France and abroad, was unani• a recent paper on the subject, alludes to a medusa, Cunina, the mously decreed to MM. Bouquet de la Grye, de Bernardieres, hydroid form of which is parasitic on the stomach of another Courcelle-Seneuil, Fleuriais, Hatt, Perrotin, Bassot, Bigourdan, medusa, Turritopsis. This hydroid produces medusre by gem• and Callandreau, chiefs of the various French expeditions sent to mation, but is itself finally modified into a medusa. observe the transit of Venus on December 6, 1882. In this The contrast between this and the more usual case is thus :- branch the Valz Prize was assigned to M. Stephan, Director of Cunina Ordinary Forms the Marseilles Observatory, and discoverer of about 700 nebulae, Egg Ercgth_ the positions of over 500 of which he has carefully determined. I For his extensive labours in the field of Experimental Physics H ydra--Hydra--Hydra M. Henri Becquerel was rewarded with the Lacaze Prize, the becomingLarvai - { Adult } I I only one given away in this department. { adult Medusa Medusa In Chemistry the J ecker Prize was secured by M. Etard for his numerous researches and publications on organic chemistry. Similarly in the Cestodes it is usually allowed that the Echino• M. L. Cailletet obtained in this branch the Lacaze Prize for his coccus stage consists in the production of a number of individuals important researches on the liquefaction of gases, and esper ·ally in the larval state, not of adults differentiated to meet diverse for his success in, for the first time, demonstrating the pm sibility methods of reproduction. of liquefying all the so-called permanent gases. In such a form as Doliolum, and indeed generally among the In Geology the Grand Prize granted by the Minister of Finance Tunicata, there seems to be more difficulty attending this view. for the best geological description of any region in France or Gemmation does not result in the production of individuals like Algeria fell to M. Fontannes for his long and succe,sful. re• the gemmating zooid, which by growth become unlike it. The searches in the Tertiary Basin of South-East France, m i:nly cyarhozooid, or the Doliolum with dorsal slolon, not only do not embodied in his "Stratigraphic and Palreontological Stuclic, of become sexual after a metamorphosis, but they give rise to the the Tertiary Period in the Rhone Valley." An exceptional award ascidiozooid, a form with ventral stolon in no way comparable of 2000 francs was also made in favour of M. Peron, author of to the adult of which it is the arrested larva. It seems here an extremely important work entitled "Essay on a Geological more probable that the existence of two methods of reproduc• Description of Algeria." tion perhaps taking place at slightly different times has led to For his comprehensive monograph on Trichinosis, M. Joannes the selection of two sets of individuals. one better fitted for Chatin Director of the Government Laboratory at Havre, ob• gemmation, the other for sexual reproduction. \Ve must then tained the Barbier Prize ; and MM. G. Bonnier and L. Mangin suppose that any influence acting for the modification of one the Desmazieres Prize for their memoir on the " Respiratioh and generation is transmitted not to the next but the next but one. Transpiration of Fungi," both in the department of Botany. In 1 1 Huxley ::; dhtin( fen of tn:e ova ard i_ seud-ova a::-,i e:,rs Lot to hol:l. the same department M. Costantin was the successful competitor

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