24 Darwinism and Other Essays. 



most widely at the top, is just what is presupposed 

 by the Darwinian theory of &quot; descent with mod 

 ification,&quot; and on any other theory it appears to 

 be totally inexplicable. 



Precisely similar testimony as to gradual diver 

 gence is found in the facts of embryology and 

 morphology. It is a familiar fact that the germs 

 of all organisms are like each other, and are, 

 moreover, very like such lowest forms of life as 

 the amoeba and protococcus. But as a germ de 

 velops it becomes specialized and defined, first 

 as to its sub-kingdom, then as to its class, order, 

 family, genus, species, and variety. The germ- 

 cell of a mandril is at first indistinguishable from 

 that of a snail or lobster. The foetal ape arising 

 therefrom is at first definable as a vertebrate, 

 but not as a mammal ; on the other hand, it cir 

 culates its blood through a system of gills, and 

 its nascent heart is like the heart of a fish. Pres 

 ently, with the appearance of the allantoidal 

 membrane, the foetus seems to be on the point of 

 becoming a reptile or bird ; but after a while it 

 declares itself a mammal. Next it becomes ap 

 parent that it is not a rodent or insectivore, but 

 a primate ; next, it exhibits characteristics which 

 define it as a true ape, and not a lemur ; still later, 

 it is seen to be a catarrhiue ape ; and finally, it 



