Origin of Different Kinds of Adaptations 349 



its environment can easily be overstepped without danger. 

 The enormous claw of the fiddler-crab must throw the 

 animal out of all symmetrical relation with its environment, 

 and yet the species flourishes. The snail carries around a 

 spiral hump that is entirely out of symmetrical relation with 

 the surroundings of a snail. 



These facts, few though they are, yet suffice to show, I 

 believe, that the relation of symmetry between the organism 

 and its environment may be, and is no doubt in many cases, 

 more perfect than the requirements of the situation demand. 

 The fact that animals made unsymmetrical through injuries 

 (as when a crab loses several legs on one side, or a worm its 

 head) can still remain in existence in their natural environ- 

 ment, is in favor of the view that I have just stated. By 

 this I do not mean to maintain that a symmetrical form does 

 not have, on the whole, an advantage over the same form 

 rendered asymmetrical, but that this relation need not have 

 in all forms a selective value, and if not, then it cannot be 

 the outcome of a process of natural selection. 



To sum up : it appears probable that the laws determining 

 the symmetry of a form are the outcome of internal factors, 

 and are not the result either of the direct action of the en- 

 vironment, or of a selective process. The finished products 

 and not the different imperfect stages in such a process, are 

 what the inn er or ganization offers to the£nvH=en-ment. 

 While the symmetry or asymmetry may be one of the numer- 

 ous conditions which determine whether a form can per- 

 sist or not, yet we find that the symmetrical relations may 

 be in some cases more perfect than the environment actually 

 demands ; and in other cases, although the form may place 

 the organism at a certain disadvantage, it may still be able . 

 to exist in certain localities. 



