7588 Notices of New Books. 



that any organic property, being common to several organisms, would 

 involve community of character in some other parts ; these, again, 

 would involve other points of resemblance, and so on and on, till we 

 get that exquisitely complex system of resemblances which co-exist 

 within each organic kingdom. 



The grounds upon which Mr. Darwin examines the phenomena of 

 Embryology, as bearing on his theory, is the assumption that, at what- 

 ever age any variation would first appear in the parent, it would tend 

 to reappear at a corresponding age in the offspring; and as a modifi- 

 cation by external influences in the struggle for existence cannot take 

 place in the foetal or early stages of life, he expects to find in the 

 embryo and young animal an epitome of the being as it existed unmo- 

 dified by external influences. He says that there is no valid reason 

 in the economy of life why the foetus should not be developed with all 

 the elaborations of the parent, but, assuming the existing organic 

 beings have multiplied and diverged in character from simpler types, 

 he sees in the simplicity of the foetus a resemblance to those simpler 

 types. He expects to find in it the absence of characters which have 

 since specialized the improved forms to particular spheres of existence, 

 and the existence perhaps of a few characters, which would be obli- 

 terated by disuse, in the multiplied descendants, occupying individu- 

 ally more limited functions. Here and there it is expected that the 

 foetus will reveal bonds of old relationship, which in the adult have 

 been obliterated by the development of characters distinguishing more 

 special functions, ^.(7., the occasional appearance of faint bars and 

 shoulder stripes in the foal of the horse and of the ass reveal, he says, 

 their common origin with the zebra, and the much closer resemblance 

 of the spotted young of the blackbird and ouzel to the thrush than 

 when matured implies modern divergence in character from some 

 ancient common progenitor ; again, that the faint bars noticeable in 

 the young cub of the lion point to its community of descent with the 

 tiger and cat, the more individual characters of the genera intensified 

 on maturity having been produced by the divided progeny of some 

 older type filling more special places in the circle of organic life. In 

 animals, as the horse, dog and pigeon, where the breeds are very 

 various, the differences characterising them are less strikingly deve- 

 loped in the young animal than the adult, pointing, on the principle 

 before mentioned, to the nearer resemblance of the parents before they 

 had assumed the fully-developed characters of their respective breeds. 

 Mr. Darwin says, at page 438 (first edition) :— " The embryo of distinct 

 animals within the same class are often strikingly similar ; a better 



