56 MEMOIRS OF 



One of the most important questions treated of in this 

 work is that of the alteration in animal forms : whether 

 the forms of lost animals, which differ so much from those 

 which are now living, really indicate species and genera 

 distinct from species and genera now existing, or if time 

 alone has modified the primitive forms, so as to attain the 

 present form. The examination of this question alone 

 would give a satisfactory answer (could they be convinced) 

 to those who believe in the indefinite alteration of forms in 

 organized beings, and who think that, with time and habits, 

 each species might have made an exchange with another, 

 and thus have resulted from one single species. However 

 extraordinary and incomprehensible this system may appear 

 to be, which would take away the basis on which science 

 rests, and which could only be established by a definition of 

 the possible duration of a species in its original state. M. 

 Cuvier, seriously refutes it, and destroys it with one objec- 

 tion, that of not finding intermediate modifications between 

 an animal of the former and present world, even when it 

 approaches it most nearly. He gives the definition of a spe- 

 cies, proves the constancy of certain conditions of the forms 

 which characterize it, and presents a table of the variations 

 which it is possible for it to undergo. In short, he demon- 

 strates, by a scrupulous examination of the skeletons of mum- 

 mies, that the animals living in Egypt two or three thousand 

 years back, when compared with those which now breathe 

 on this classic ground, have not. in the course of so many 

 ages, undergone any important changes of form ; that even 

 among the wild animals there has been no alteration in the 

 skeleton which could characterize one race or variety. 

 " There is nothing," to use M. Cuvier's own words, " which 

 can in the least support the opinion, that the new genera 

 which I and other naturalists have discovered or established 

 among fossils, the Paleotherium, the Anoplotherium, &c., 

 have 'been the parent stocks of some of the present ani- 

 mals, which only differ from them in consequence of other 

 soil, climate." &c. Further on he continues, " When I 

 maintain that stony strata contain the bones of several gene- 

 ra, and moveable earths those of several species which no 

 longer exist, I do not pretend that a new creation has been 

 necessary to produce the existing species. I merely say 



