Origin of Different Kinds of Adaptations 357 



Thus, from the point of view that is here taken, an animal 

 does not become degenerate because it becomes parasitic, 

 but the environment being given, some forms have found 

 their way there ; in fact, we may almost say, have been 

 forced there, for these degenerate forms can only exist under 

 such conditions. 



In conclusion, this much at least can be claimed for the 

 mutation theory ; that it meets with no serious difficulty in 

 connection with the phenomena of degeneration. It meets 

 with no difficulty, because it makes no pretence to explain 

 the origin of adaptations, but can account for the occurrence 

 of degenerate forms, if it is admitted that these appear as 

 mutations, or as definite variations. Let us, however, not 

 close our eyes to the fact that there is still much to be 

 explained in respect to the degeneration of animals and 

 plants. It is far from my purpose to apply the mutation 

 theory to all adaptations ; in fact, it will not be difficult to 

 show that there are many adaptations whose existence can 

 have nothing directly to do with the mutation theory. 



Protective Coloration 



That many species of animals are protected by their re- 

 semblance to their environment no one will probably deny. 

 That we are ignorant in all cases as to how far this protec- 

 tion is necessary for the maintenance of the species must be 

 admitted. That some of the resemblances that have been 

 pointed out have been given fictitious value, I believe very 

 probable. 



Resemblance in color between the organism and its en- 

 vironment has given to the modern selectionist some of his 

 most valuable arguments, but we should be on our guard 

 against supposing that, because an animal may be protected 

 by its color, the color has been acquired on this account. 

 On the supposition that the animal has become adapted by 



