OBJECTIONS AGAINST EVOLUTION. 159 



transmutation of the species named. For it must 

 be borne in mind, that all species are not equally 

 susceptible of change in consequence of mutations 

 of climate and physical geography. Some are more 

 stable and more cosmopolitan than others, and 

 hence are capable of accommodating themselves 

 within certain limits to quite considerable changes 

 in surrounding conditions, without exhibiting the 

 slightest indications of specific transmutations. 



Then, too, we have " elastic types," those types, 

 namely, which as M. Gaudry tells us, have the 

 power of undergoing greater or less modifications 

 and of returning sooner or later to their original 

 condition. The rhynconella is a case in point. 

 When the ocean bed is in anywise modified, rhyn- 

 conella exhibits a corresponding change ; when the 

 ocean returns to its original state, rhynconella re- 

 verts to its pristine condition. Thus, in virtue of 

 its elasticity, of its facility of accommodating itself 

 to changes of environment, this marvelous brachio- 

 pod has been able to pass unscathed through 

 mutations and catastrophes innumerable. 



Again, it may be observed, that the changes of 

 environment are not always so great as they are 

 sometimes imagined to be. Thus, the conditions of 

 life in a given area of the ocean may remain practi- 

 cally unchanged for long geological periods. The 

 temperature and depth of the water might easily 

 remain constant for untold aeons, and, in such an 

 event, there is no reason why the ocean fauna should 

 not endure without variation for an indefinite 

 time. 



