284 TJie American Natu 



[April, 



fense among men. After thousands of years of war with un- 

 armored bodies, men began to use defensive armor, the body 

 becoming more and more covered, until it was completely 

 clothed in iron mail, and became rigid and sluggish. In the 

 subsequent period offensive weapons became able to pierce this 

 iron covering, and it was finally thrown aside as cumbrous and 

 useless. A similar process is now going on in the case of war 

 vessels, they being clad in heavy armor, which may yet be ren- 

 dered useless by the development of cannon of superior pierc- 

 ing powers, and be discarded in favor of the light and nimble 

 unarmored ship. 



The analogy to animal evolution in this is singularly close. 

 After long ages of active warfare between naked animals, 

 defensive armor was assumed by nearly every type of life, ex- 

 cept the lowest, highly prolific forms, and the highest, which 

 had no foes to fear. But the powers of offense grew also, and 

 in time the employment of armor ceased, as no longer avail- 

 able, its last important instance being that of the ganoid fishes. 

 The later fish reduced their armor to thin scales, and gained 

 speed and flexibility in proportion, while in land animals 

 armor was seldom assumed. In several instances creatures 

 have gone back to the old idea, as in the armadillo, the porcu- 

 pine, the turtle, etc., but the thinly clad, agile form has be- 

 come the rule, armor no longer yielding the benefit that was 

 derived from it in the days of weak powers of offense. This 

 result is a fortunate one, since with increase of agility mental 

 quickness has come into play, the result being a development 

 of the mind in place of the old development that was almost 

 wholly confined to the body. In the highest form of all, that 

 of man, physical variation has almost ceased, in consequence 

 of the superior activity of mental evolution. 



In conclusion it must be admitted that there are certain for- 

 mations in nature which seem to militate against the argument 

 here advanced. I have already spoken of the much questioned 

 Eozoon canadense. In addition there are the beds of lime- 

 stone and graphite in the Laurentian formation. But these 

 prove too much for the advocates of their organic origin. If 

 so large a fossil as Eozoon had appeared so early, the subse- 



