DESCENT OF MAN FROM SOME LOWER FORM. 133 



dissimilar. A better proof of this latter fact can not be 

 given than the statement by Von Baer that "the em- 

 bryos of mammalia, of birds, lizards, and snakes, prob- 

 ably also of chelonia, are in their earliest states exceed- 

 ingly like one another, both as a whole and in the mode 

 of derelopment of their parts ; so much so, in fact, that 

 we can often distinguish the embryos only by their size. 

 In my possession are two little embryos in spirit, whose 

 names I have omitted to attach, and at present I am 

 quite unable to say to what class they belong. They may 

 be lizards or small birds, or very young mammalia, so 

 complete is the similarity in the mode of formation of 

 the head and trunk in these animals. The extremitieSj^ 

 however, are still absent in these embryos. But, even if 

 they had existed in the earliest stage of their develop- 

 ment, we should learn nothing, for the feet of lizards and 

 mammals, the wings and feet of birds, no less than the 

 hands and feet of man, all arise from the same funda- 

 mental form." The larvas of most crustaceans, at corre- 

 sponding stages of development, closely resemble each 

 other, however different the adults may become ; and so 

 it is with very many other animals. A trace of the law of 

 embryonic resemblance occasionally lasts till a rather late 

 age : thus birds of the same genus, and of allied genera, 

 often resemble each other in their immature plumage ; as 

 we see in the spotted feathers in the young of the thrush 

 group. In the cat tribe, most of the species when adult 

 are striped or spotted in lines ; and stripes or spots can 

 be plainly distinguished in the whelp of the lion and the 

 puma. We occasionally though rarely see something of 

 the same kind in plants ; thus the first leaves of the ulex 

 or furze, and the first leaves of the phyllodineous acacias, 

 are pinnate or divided like the ordinary leaves of the 

 LeguminoscB. 



