92 THE DOCTRINE OF DESCENT. 



of species. The literature of ornithology during the last 

 forty years could furnish thousands of the strangest ex- 

 amples of the Babel-like confusion which was thus intro- 

 duced. 



There is no question that a great, perhaps the greater, 

 number of organisms now existing are in a condition 

 in which, according to their internal and external rela- 

 tions, they may be characterized by Natural History as 

 so-called species, and for the purpose of recognition and 

 scientific treatment in general, must needs be so charac- 

 terized. But this stability, as may be shown both directly 

 and by analogy, is under all circumstances only tem- 

 porary, and we have whole classes of organisms to which 

 it is impossible, even with the widest reservations, to ap- 

 ply the old idea of species, with its immutability of essen- 

 tial characteristics. If we are able to furnish incontro- 

 vertible proofs of the existence of such non-specific 

 groups, the old system and the dogma of species are once 

 for all set aside, and the positive basis of a new doctrine 

 is secured. This evidence is supplied in two directions. 

 Some classes of organisms in their present state vacillate 

 and fluctuate in form, in such a manner that it is utterly 

 impossible to fix the characteristics of species or genus. 

 They are in an extreme grade of mutability, which, in 

 others, has given way to an apparent state of repose. 

 Other series of facts, exhibiting the most obvious muta- 

 bility of species, are displayed by certain antediluvian 

 groups in the succession of forms called " species." 



Even before the appearance of Darwin's work on the 

 " Origin of Species," Carpenter, in the course of his re- 

 searches on the Foraminifera, arrived at the conclusion, 

 proved in special instances, that in this group of low 



