264 THE CHAIN OF LIFE. 



that would bafile Omnipotence itself, because they are simply 

 absurd. In this aspect of them, indeed, such speculations arc 

 necessarily futile, because no mind can grasp all the complexities 

 of even any one case, and it is useless to follow out an imaginary 

 line of development which unexplained facts must contradict 

 at every step. This is also no doubt the reason why all 

 recent attempts at constructing " Phylogcnies " are so change- 

 able, and why no two experts can agree about almost any 

 of them. 



A second aspect in which such speculations are too partial 

 is in the unwarranted use which they make of analogy. It is 

 not unusual to find such analogies as that between the em- 

 bryonic development of the individual animal and the succession 

 of animals in geological time placed on a level with that 

 reasoning from analogy by which geologists apply modern 

 causes to explain geological formations. No claim could be 

 more unfounded. When the geologist studies ancient lime- 

 stones built up of the remains of corals, and then applies the 

 phenomena of modern coral reefs to explain their origin, he 

 brings the latter to bear on the former by an analogy which 

 includes not merely the apparent results but the causes at work, 

 and the conditions of their action ; and it is on this that the 

 validity of his comparison depends, in so far as it relates to 

 similarity of mode of formation. But when we compare the 

 development of an animal from an embryo cell with the pro- 

 gress of animals in time, though we have a curious analogy as 

 to the steps of the process, the conditions and agents at work 

 are known to be altogether dissimilar, and therefore we have 

 no evidence whatever as to identity of cause, and our reasoning 

 becomes at once the most transparent of fallacies. Farther, 

 we have no right here to overlook the fact that the conditions 

 of the embryo are determined by those of a previous adult, 

 and that no sooner does this hereditary potentiality produce a 

 new adult animal than the terrible external agencies of the 

 physical world, in presence of which all life exists, begin to 



