E VI DEN CBS OF E VOL UTION. 133 



the as yet vast and unexplored regions of the earth 

 shall have yielded up a portion of their fossil treas- 

 ures, can easily be divined. Already the general- 

 ized fossil types which have been discovered, have 

 completely revolutionized all systems of classifica- 

 tion which were based on existing specialized forms. 

 For, by tracing the widely separated groups of the 

 present back to past geologic time, we find that 

 the specialized types of our day gradually converge 

 towards, and merge into, the generalized types long 

 since extinct. Species the most diverse gradually 

 approach each other, and eventually unite to form 

 common branches, and these again coalesce in a 

 common trunk. 1 



And this is just what the theory of Evolution 

 demands. For, " If the theory of Evolution be 

 true," says Huxley," it follows that however diverse 

 the different groups of plants and of animals may 

 be, they must all, at one time or other, have been 

 connected by gradational forms ; so that, from the 

 highest animals, whatever they may be, down to 

 the lowest speck of protoplasmic matter in which 

 life may be manifested, a series of gradations, lead- 

 ing from one end of the series to the other, either 

 exists or has existed." " 



l " Hence," declares Huxley, in his article on Classification 

 in the Encyclopaedia Britannica, " it follows that a perfect and 

 final zoological classification cannot be made until we know all 

 that is important concerning: i, the adult structure; 2, the per- 

 sonal development; 3, the ancestral development of animals. 

 It is hardly necessary to observe that our present knowledge, 

 as regards even the first and second heads, is very imperfect ; 

 while as respects the third it is utterly fragmentary. 



a " Lectures on Evolution." Lecture II. 



