December 22, 1898J 



NA TURE 



171 



Sauropsiden " is a conclusion arrived at from structural, 

 grounds, or if it in turn is responsible for the acceptance 

 of certain morphological conclusions. One, out of many, 

 is the sanction given to the startling attempt made by 

 his prosector, to derive the hair from something older 

 than Sauropsidan structures, namely, from certain 

 degenerating sense organs of Amphibia. A very able 

 criticism of this hypothesis has, by the way, been given 

 by Keibel in Merkel and Bonnet's periodical. The same 

 idea of relationship underlies the treatment of the skin- 

 glands, the skeleton of the limbs, the homologies of the 

 ear-bones, iS:c. 



The paragraphs dealing with the vertebral column are 

 not a success ; the question is left where Klaatsch left it 

 in 1S95, and that does not go beyond the cartilaginous 

 fishes ; the rest is written on the old futile lines. Nor 

 can much praise be bestowed upon the treatment of the 

 ribs, in which — instead of his old well supported teaching 

 — a compromise has been made adopting the view of the 

 existence of upper and lower ribs, mixing up thereby true 

 ribs and other parts, which, although likewise differenti- 

 ations of ventral arches, are not, nor ever were ribs. .At 

 the same time there is a tenacious pleading for the 

 correctness of his original view. One of the causes of 

 this uncertain state is the wholesale adoption of the 

 results arrived at by one of his assistants. 

 ■ Perhaps all through the book an easily understood, but 

 nevertheless somewhat undue preference is given to 

 papers published in the Mcrfphologische Jahrbuch. Here- 

 with is connected a peculiar treatment of the literature, 

 which shows many deficiencies, more due to design than 

 to accident, because the author says pointedly that he 

 has restricted himself to the most important writings. 

 Anyhow, this may be said in explanation : The MS. 

 seems to have been practically finished several years ago, 

 and little notice has been taken of what has been 

 published since, except the work done by those with 

 whom the author has been more or less in contact, bring- 

 ing thereby some additions down to even last year's 

 publications. 



The genesis of the Chelonian carapace is a most 

 suggestive chapter, but difficult reading, especially since, 

 a page or two further on, the right of existence of an 

 alternative view is conceded, namely, that neural and 

 costal plates may after all be of dermal origin. Dermo- 

 chelys, in support of the leading view in the text, is 

 pronounced to be a low, most primitive form, but a little 

 further on the mosaic shield of this turtle is confessed to 

 be in a state of retrogression. 



The visceral, branchial skeleton of the Cyclostomes 

 (p. 415) is of ectodermal origin. "It must, however, 

 have been derived from the cranial cartilage, for we cannot 

 possibly side with the old teleological notion that this 

 cartilage arises in the ectoderm in situ of the future 

 branchial skeleton, and develops itself into the necessary 

 branchial arches. A small interbranchial bit of cartilarge, 

 consisting perhaps of a few cells only, would be of no 

 use, and, moreover, why should such isolated bits of 

 cartilage cells turn up there? But the assumption that 

 the branchial apparatus arises as little processes of the 

 already existing cranium, gives them at once a supporting 

 function." Then follows a beautiful, lucid description of 

 the branchial skeleton of the Gnathostomata, the whole 

 NO. I 52 I, VOL. 59] 



long chapter, from Elasmobranchs to the highest 

 Mammalia, with all the marvellous modifications, ulti- 

 mately into hyoid, epiglottic and laryngeal appiratus 

 being welded into an harmonious illustration of onward 

 evolution. 



On p. 460, in winding up with a fascinating ri'sume 

 concerning the emancipation of the head from the rest of 

 the body, the author takes the opportunity of severely 

 reproaching the embryologists. 



" Comparison teaches us that the visceral arches of 

 the Amniota are derived from branchial arches ; the 

 descriptive method reveals only the differences, and 

 takes no stock of the fact that these gill-less visceral 

 arches were once gill-bearing arches. This knowledge is 

 the result of the comparative method and of conclusions 

 based upon these facts, conclusions which stand in contra- 

 diction to ontogenetic experience. But while this has not 

 prevented any one from acknowledging the homologies 

 of visceral and branchial arches, the same kind of con- 

 clusion when applied to the cranium [namely, to its 

 metameric origin] meets with objections." 



But was this outburst necessary ? Who, having fol- 

 lowed the last ten years of extremely active, and chiefly 

 embryological research, does now object to the metameric 

 composition of the head .^ 



Curiously enough, his famous theory of the origin of 

 the limbs and their girdles from visceral arches is only 

 sketched in the very outlines. He devotes but a few 

 very critical remarks to the important support, which his 

 theory has gained from ontogenetic research, and how 

 far ontogeny can be expected to yield results. This is 

 surprising,because nobody, unlesshehasstudied the whole 

 question and the literature attentively, will be convinced 

 by the perusal of the few pages 461-466. We had the 

 right to expect a critical marshalling of the whole 

 apparatus of comparative anatomy, with the numerous 

 points in favour, drawn from the skeletal, muscular, and 

 nervous systems, and refutation of the almost equally 

 numerous mistaken contrary comments. The derivation 

 and evolution of the free limb is, however, done 

 splendidly, although we miss a discussion of the axis of 

 the dactyloid limb. The author himself says, in the 

 preface, that he could not treat everything with equal 

 fulness, but there are not a few points on which we should 

 have liked this very authority's opinion. We look, how- 

 ever, in vain for more than a passing remark under 

 epitrichium, subnotochordal rod, proatlas, pisiform bone, 

 OS acetabuli, &c. He holds that there were never more 

 than five fingers " unless a creature can be shown which 

 normally possessed more." .All the so-called vestiges of 

 additional fingers and toes are discarded summarily ; but- 

 might not Kukenthal's discovery of excalation of fingers 

 in the Cetacea have been given at least passing consider- 

 ation ? 



More than 100 pages are devoted to the muscular 

 system, making quite a new feature in a text-book, con- 

 sidering how scantily it had been treated hitherto from a 

 general point of view. It is the first successful attempt 

 to bring the mass of accumulated observations into one 

 frame, beginning with the invertebrate conditions as the 

 fundamental starting-point, and then paying especial 

 attention to the musclesof the head, and to the derivation 

 of those of the limb from the truncal system. The nerve- 

 supply is of course taken as the guide, while the almost 



