NATURE 



517 



THURSDAY, OCTOBER 18, 1877 



HUXLE Y'S "ANA TOMY OF INVERTEBRA TED 



ANIMALS" 

 A Maiitial of the Anatomy of Inverlebratcd Animals. 



By Thomas H. Huxley, LL.D., F.R.S. (London : 



Churchill, 1S77.) 



IN the year 1871 Prof. Huxley published a Manual of 

 the Anatomy of Vertebrated Animals as the first part 

 of a treatise on Comparative Anatomy. By the publica- 

 tion during the present autumn of the work now about to 

 be noticed, he has fulfilled his undertaking to produce a 

 treatise for students on this extensive and complex branch 

 of anatomical inquiry. As might be expected from the 

 author's well-won reputation, not only as a philosophical 

 thinker and scientific observer, but as extensively read in 

 the literature of his subject, the work is one which, in 

 proportion to its size, furnishes the student with the most 

 compact account of the present aspect of the science of 

 comparative anatomy in the English language. 



In writing a work on comparative anatomy, two modes 

 of arranging and classifying the multitude of facts that 

 are to be considered may be pursued by an author. In 

 the one, which may be called the anatomico-physiological 

 method, he may take as the basis of his arrangement the 

 several organs found in the animal body, and may trace 

 out the various modifications exhibited by each organ in 

 different animals. This plan has been pursued in the 

 well-known systematic treatises of Cuvier, Meckel, and 

 Milne- Edwards. In the other, or zoological method, 

 animals are grouped in " natural orders " according to a 

 taxonomic system, and the anatomical characters of the 

 animals belonging to each of these orders are described 

 and compared with each other. Siebold, Stannius, Owen, 

 and Gegenbaur adopted this mode of arrangement, and 

 a somewhat similar plan has been carried out by the 

 author of the work before us. 



Although the anatomico-physiological method is not 

 without its advantages to a particular class of readers, yet 

 the zoological basis of arrangement is, we think, more 

 generally useful, as it enables the reader to acquire by the 

 perusal of a single chapter, a knowledge of the anatomy 

 of a given natural order of animals, instead of having to 

 pick out from a number of different chapters the vaiious 

 facts bearing on their structure. 



In carrying out this plan Prof. Huxley has selected for 

 special and more elaborate description a characteristic 

 specimen of each group or order, whilst the other 

 members of the same group or order are either only 

 incidentally alluded to, or merely the chief features of 

 difference between them and the selected specimen are 

 pointed out. For a student's book this is unquestionably 

 the most suitable plan, as it gives him the means of 

 perusing, within the compass of a moderate-sized volume, 

 a carefully drawn-up account of well-marked examples of 

 the various orders, without confusing him with a multi- 

 tude of subordinate facts which it would be difficult to 

 keep in mind, whilst it facilitates practical study by 

 supplying a somewhat full description of individual forms. 

 In addition to the description of adult forms much infor- 

 mation is also communicated on the development of the 

 Vol, XVI.— No. 416 



animals described, and the facts of embryology are made 

 to throw much valuable light on the details of structure. 



To the general reader the most interesting sections of 

 the book are the introduction and the first and last chap- 

 ters. The introduction commences by pointing out that 

 the distinctiveproperties of living matter are due to its 

 chemical composition, to its universal disintegration and 

 waste by oxidation, and its concomitant reintegration by 

 the intus-susception of new matter, and to its tendency to 

 undergo cyclical changes. A number of interesting ex- 

 amples are then given of the dependence of all the activi- 

 ties of living matter upon moisture, and upon heat 

 within a limited range of temperature. The arguments 

 which have been advanced in favour of the origin 

 of living from non-living matter, or abiogenesis, as 

 it is now termed, are then considered. The conclu- 

 sion is come to that there is no ground for assuming, 

 as is done by the supporters of the hypothesis of 

 abiogenesis, that all living matter is killed at some given 

 temperature — between 104° and 208^ F., so that the evi- 

 dence adduced in its favour, from the experiments where 

 organic infusions have been subjected to this high tem- 

 perature, is logically insufficient to furnish proof of its 

 occurrence.^ Prof. Huxley abides, therefore, by the 

 opinion expressed in his well-known Liverpool Address 

 to the British Association on this subject. There is no 

 necessary connection as has sometimes been assumed 

 between the theory of evolution and a belief in the 

 occurrence of abiogenesis as a mode of origin of living 

 things at the present day. Life must at one lime have 

 been breathed into non-living matter, but there is nothing 

 to show that existing organisms, or those occurring in 

 any recorded epoch of geological time, have had any 

 other origin than from pre-existing forms of life. 



It has been assumed by many writers that the deve- 

 lopmental changes, which an organism passes through 

 during its embryonic existence, furnish a key to decipher 

 the full pedigree of the organism and proclaim its family 

 history. So keenly has this branch of biological specu- 

 lation or phylogeny, as it is termed, been followed out by 

 some naturalists, that they have based their systems of 

 classification on the supposed ancestral history of 

 animals. We are glad to find that Prof. Huxley inter- 

 poses some wise words of caution on this matter. The 

 reconstruction of the pedigree of a group from the de- 

 velopmental history of its existing members is, he says, 

 fraught with difficulties. And again, of the numerous 

 phylogenic hypotheses which have of late come into 

 existence, few have any other significance than as 

 suggesting new lines of investigation ; in the absence of 

 any adequate pateontological history of the Invertcbrata, 

 any attempt to construct their phylogeny must be mere 

 speculation. It is to be hoped that this protest against 

 the fanciful hypotheses of some phylogenists, a protest 

 which might have been unheeded if it had emanated 

 from an opponent of the doctrine of evolution, may, seeing 

 that it comes from him, who by the lucidity, vigour, and 

 logical power of his writings, has, next to the illustrious 

 Darwin, done more to gain credence for the doctrine, 

 than any other writer, check the tendency to hasty 

 speculation in this direction, in which some naturalists 

 have of late indulged. 



Had space permitted we should have liked to have 



CO 



