IN MODERN SCIENCE. 



75 



changes ; but the results have been unsatisfac- 

 tory, and our author scarcely condescends to 

 notice this line of proof. He evidently regards 

 the time over which human history has extended 

 as too short to admit of this kind of demon- 

 stration. Secondly. There might be in the exist- 

 ing system of nature such a close connection 

 or continuous chain of species as might at least 

 strengthen the argument from analogy ; and 

 undoubtedly there are many groups of closely 

 allied species, or of races confounded with true 

 specific types, which it might not be unreason- 

 able to suppose of common origin. These are, 

 however, scattered widely apart ; and the con- 

 trary fact of extensive gaps in the series is so 

 frequent, that Haeckel is constantly under the 

 necessity of supposing that multitudes of 

 species, and even of larger groups, have 

 perished just where it is most important to 

 his conclusion that they should have remained. 

 This is, of course, unfortunate for the theory ; 

 but then, as Haeckel often remarks, " we must 

 suppose " that the missing links once existed. 

 But, thirdly, these gaps which now unhappily 

 exist may be filled up by fossil animals ; and 

 if in the successive geological periods we could 

 trace the actual phylogeny of even a few groups 



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