312 THE GENESIS OF SPECIES. [CHAP. 



Professor Agassiz objects to the evolution theory, on the 

 ground that " species, genera, families, &c., exist as thoughts, 

 individuals as facts/' 1 and he offers the dilemma, "If 

 species do not exist at all, as the supporters of the trans- 

 mutation theory maintain, how can they vary ? and if 

 individuals alone exist, how can the differences which may 

 be observed among them prove the variability of species ? " 



But the supporter of "evolution" need only maintain 

 that the several " kinds " become manifested gradually by 

 slight differences among the various individual embodi- 

 ments of one specific idea. He might reply to the dilemma 

 by saying, species do not exist as species in the sense in 

 which they are said to vary (variation applying only to the 

 concrete embodiments of the specific idea), and the evolu- 

 tion of species is demonstrated not by individuals as indi- 

 viduals, but as embodiments of different specific ideas. 



Some persons seem to object to the term " creation " 

 being applied to evolution, because evolution is an " ex- 

 ceedingly slow and gradual process." Now even if it were 

 demonstrated that such is really the case, it may be asked, 

 what is " slow and gradual " ? The terms are simply rela- 

 tive, and the evolution of a specific form in ten thousand 

 years would be instantaneous to a being whose days were 

 as millions of millions of years. 



There are others again who are inclined to deny the 

 existence of species altogether, on the ground that their 

 evolution is so gradual that if we could see all the stages 

 it would be impossible to say when the manifestation of 

 the old specific form ceased and that of the new one began. 

 But surely it is no approach to a reason against the exist- 



1 American Journal of Science, July 1860, p. 143, quoted in Dr. Asa 

 Gray's pamphlet, p. 47. 



