\'2'2 SPECIES NOT 



count. He can see no explanation of the fact 

 in special creation, but can easily understand it 

 on the view that groups of species have descended 

 from other species, and Ifave been modified by 

 "natural selection." In the earlier part of the 

 volume, and frequently in its course, Mr. D. dwells 

 upon the enormous number of generations neces- 

 sary to produce the transmutation of species. He 

 now, however, thinks that an extraordinary 

 amount of modification, though large and long- 

 continued, implies that this has been within a 

 in'riod not excessively remote, "as species very 

 rarely endure for more than one geological period." 

 This statement is made to account for the "va- 

 riability" of one organ, as compared with "other 

 parts of the organization, which have remained 

 for a much longer period nearly constant." 



Going onwards, Mr. D. states "that the most 

 abnormally-developed organs may be made con- 

 stant, I can see no reason to doubt." Thus, 

 "the wing of the bat having been transmitted, 

 in approximately the same condition to many 

 modified descendants, must have existed, according 

 to my theory, for an immense period in nearly 

 the same state." 



Now I think it is impossible to conceive a 

 more unsatisfactory mode of arguing out a ques- 

 tion than this. Because the wing of the bar 

 does not vary and support Mr. D.'s theory, 

 therefore it is an abnormity. 



This large family of most useful insectivorous 

 creatures, found in all parts of the world, and 



