60 ESSAY ON CLASSIFICATION 



have existed different species; but no transition from those of a pre- 

 ceding into those of the following epoch has ever been noticed any- 

 where; and the question alluded to here is to be distinguished from 

 that of the origin of the differences in the bulk of species belonging 

 to two different geological eras. The question we are now examining 

 involves only the fixity or mutability of species during one epoch, 

 one era, one period in the history of our globe. And nothing fur- 

 nishes the slightest argument in favor of their mutability; on the con- 

 trary, every modern investigation"^^ has only gone to confirm the re- 

 sults first obtained by Cuvier and his views that species are fixed. 



It is something to be able to show by monumental evidence, and 

 by direct comparison that animals and plants have undergone no 

 change for a period of about five thousand years."^^ This result has 

 had the greatest influence upon the progress of science, especially 

 with reference to the consequences to be drawn from the occurrence 

 in the series of geological formations of organized beings as highly 

 diversified in each epoch as those of the present day;^" it has laid the 

 foundation for the conviction, now universal amonsr well informed 

 naturalists, that this globe has been in existence for innumerable 

 ages and that the length of time elapsed since it first became in- 

 habited cannot be counted in years. J^ven the length of the period 

 to which we belong is still a problem, notwithstanding the precision 

 with which certain systems of chronology would fix the creation of 



the first introduction of animals or plants upon earth, not the slightest evidence has 

 yet been produced that species are actually transformed one into the other. We only 

 know that they are different at different periods, as are works of art of different periods 

 and of different schools; but as long as we have no other data to reason upon than 

 those geology has furnished to this day, it is as unphilosophical and illogical, because 

 such differences exist, to assume that species do change and have changed, that is, 

 are transformed or have been transformed, as it would be to maintain that works of 

 art change in the course of time. We do not know how organized beings have origi- 

 nated, it is true; no naturalist can be prepared to account for their appearance in the 

 beginning or for their difference in different periods; but enough is known to repu- 

 diate the assumption of their transmutation, as it does not explain the facts and shuts 

 out further attempts at proper investigations. See Powell, Essays, p. 412, et seq., and 

 Essay 3d, generally. 



'* Karl S. Kunth, "Recherches sur les plantes trouv^es dans les tombeaux c^gyptiens," 

 Annates des sciences naturelles, VIII (1826), 11. 



'* It is not for me to discuss the degree of reliability of the Egyptian chronology; 

 but as far as it goes, it shows that from the oldest periods ascertained, animals have 

 been what they are now. 



* Agassiz, "The Primitive Diversity . . . ," American Journal of Science, XVII (2d 

 ser., 1854), 309-354. 



