92 THE DOCTRINE OF DESCENT. 



less fettered by tradition and law than in the definition 

 of species. The literature of ornithology during the last 

 forty years could furnish thousands of the strangest 

 examples of the Babel-like confusion which was thus 

 introduced. 



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 re- 

 lations, 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 

 characterized. But this stabiHty, as may be shown both 

 directly and by analogy, is under all circumstances only 

 temporary, and we have whole classes of organisms to 

 which it is impossible, even with the widest reservations, 

 to apply the old idea of species, with its immutability of 

 essential characteristics. If we are able to furnish incon- 

 trovertible 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 

 researches on the Foraminifera, arrived at the con- 



