50 THE HISTORY OF CREATION. 



all organic individuals wLicli were very similar, or almost 

 identical in form, and which could only be distinguished 

 from one another by very unimportant differences. On the 

 other hand, they considered as different species those 

 individuals which presented more essential or more striking 

 differences in the foiTQation of their bodies. But of course 

 this opened the flood-gates to the most arbitrary proceedings 

 in the systematic distinctions of species. For as all the 

 individuals of one species are never completely alike in 

 all their parts, but as every species varies more or less, no 

 one could point out which degree of variation constituted 

 a really " good species," or which degree indicated a "mere 

 variety.'* 



This dogmatic conception of the idea of species, and 

 the arbitrary proceedings connected with it, necessarily 

 led to the most perplexing contradictions, and to the most 

 untenable suppositions. This is clearly demonstrable in 

 the case of the celebrated Cuvier (born in 1769), who 

 next to Linnseus has exercised the gTeatest influence on 

 the study of zoology. In his conception and definition of 

 the idea of species, he agreed on the whole with Linnseus, 

 and shared also his belief in an independent creation of 

 individual species. Cuvier considered their immutability 

 of such importance that he was led to the fooUsh asser- 

 tion — " The immutability of species is a necessary con- 

 dition of the existence of scientific natural history." As 

 Linnreus' definition of species did not satisfy him, he 

 made an attempt to give a more exact and, for syste- 

 matic practice, a more useful definition, in the following 

 words : ''' All those individual animals and plants belong to 

 one species which can be proved to be either descended 



