So 



NATURE 



[March 27, 1913 



this large and finely illustrated volume is rilled, 

 for Prof. Patten has spared no labour in his en- 

 deavour to test what seems to him to be an 

 approximate solution of the problem of the evolu- 

 tion of the vertebrates. It may be said at the 

 outset that his theory is quite different from 

 Gaskell's, which, in his judgment, was vitiated 

 by the assumption that the neural surface of an 

 Arthropod is the same as the haemal surface of a 

 vertebrate. 



The general thesis is that "the great Vertebrate- 

 Ostracoderm-Arthropod phylum forms the main 

 trunk of the genealogical tree." Vertebrates 

 arose through Ostracoderms from Arachnid-like 

 Arthropods. One of the important steps was 

 cephalogenesis, numerous anterior metameres 

 being integrated into a "head " — prophetic of the 

 vertebrate head ; the old mouth was closed and 

 a new one opened ; the bases of the more anterior 

 appendages were forced towards the haemal sur- 

 face to form the vertebrate oral arches ; the heart 

 was drawn forwards ; true gill-clefts appeared ; 

 the lateral eye placodes were transferred to the 

 interior of the cerebral vesicle and the optic 

 ganglia to the roof of the mid-brain ; and so on. 



The Arachnids' forebrain vesicle is formed like 

 that of vertebrates ; both have the same sort of 

 pineal eye ; Arachnids have a cartilaginous endo- 

 cranium similar in shape and location to the 

 primordial cranium of vertebrates, and they have 

 an axial subneural rod comparable with the 

 notochord ; in Arachnids the brain contains ap- 

 proximately the same number of neuromeres as in 

 vertebrates — these are fair illustrations of the 

 arguments by which Prof. Patten supports his 

 thesis. With his guiding idea of an Arachnid- 

 Ostracoderm- Vertebrate alliance, Prof. Patten 

 feels that the numerous resemblances he adduces 

 have a cumulative convincingness. We must 

 confess that many of them appear to us exceed- 

 ingly far-fetched, e.g. that the "lemmatochord " 

 is comparable to the notochord, and that many 

 others, e.g. "endocranium " and cranium, simply 

 illustrate convergence. To the preliminary objec- 

 tion that Arachnids are far too specialised to have 

 given rise to vertebrates, the author gives an 

 answer the point of which we cannot profess to 

 see, that "every animal is a specialised one when 

 compared with its ancestors, and at the same 

 time a generalised one when compared with its 

 descendants." 



In regard to the position of other classes in- 

 volved, Prof. Patten holds remarkable views. 

 The Ostracoderms are intermediate between 

 Arachnids and vertebrates ; the Cirripedes are the 

 only members of the Acraniates in which the more 

 typical Arthropod characters are retained; the 

 NO. 2265. VOL. Ql] 



Tunicates are descended from that particular sub- 

 division of the Arthropods to which the Cirripedes 

 and Copepods belongs; the Echinoderms are also 

 descended from Cirriped-like Arthropods, as may 

 be inferred from the nauplius-like larval form ; 

 the Enteropneusta are probably descendants of 

 primitive Arthropods ; the Pterobranchs have in 

 certain respects, such as the six pairs of appen- 

 dages, a decidedly arachnoid character; the 

 Polyzoa may best be interpreted as descendants 

 of primitive Arthropods of the Cirriped type ; the 

 ( '1 seti gnatha are unquestionably primitive Arthro- 

 pods, somewhat degenerate. Thus we see how 

 the clearing up of the main highway — the 

 Arachnid-Ostracoderm-Vertebrate line — makes the 

 relations of the byways plain ! There is much to 

 be said for vigorous heresy, but this is a perver- 

 sion of morphology. We are minded, howevei', of 

 the saying of another investigator of the pedigree 

 of vertebrates, that " in morphologv everything is 

 important except the hypothesis." In conclusion, 

 we may note that Prof. Patten's researches have 

 made him a convinced "bathmist." The internal 

 processes of differential growth and readjustment 

 are fundamentally important. Environmental 

 influence, natural selection, and the like have 

 played an insignificant subordinate part. "The 

 creative power of internal environment is always 

 present, always active, always changing." We 

 conless to liking this view better than the author's 

 phylogeny. 



ZOOLOGY AND NATURAL HISTORY. 



(1) Animal Secrets Told: A Book of "JJ'hys." 

 By H. C. Brearley. With twelve full-page illus- 

 trations from photographs by Ehvin R. Sanborn. 

 Pp. xvi + 274. (London: Headley Brothers, 

 n.d.) Price 55. net. 



(2) Wild Life 111 the West Highlands. By C. H. 

 Alston. With illustrations by A. Scott Rankin. 

 Pp. xi + 271. (Glasgow : James MacLehose and 

 Sons, 1912.) Price 6s. net. 



(3) The Sheep and Its Cousins. By R. Lydekker, 

 F.R.S. Pp. xv + 315. (London: George Allen 

 and Co., Ltd., 1912.) Price 105. 6d. net. 



(4) The Marine Mammals in the Anatomical 

 Museum of the University of Edinburgh. Parti., 

 Cetacea ; Part ii., Sirenia; Part iii., Pinnipedia. 

 By Sir Wm. Turner, K.C.B. Pp. xv + 207. 

 (London: Macmillan and Co., Ltd., 1912.) 

 Price 6s. net. 



(5) The Growth of Groups in the Animal Kingdom. 

 By Prof. R. E. Lloyd. Pp. viii+ 185. (London : 

 Longmans, Green and Co., 1912.) Price 55. net. 



ANIMAL Secrets Told" (1) is a series of 

 popular articles explaining, or attempting 

 to explain, the reason for special variation in the 



