ON VARIETIES, KACES, SUB-SPECIES, AND SPECIES. 66 



of the species of organized beings. Although it is the common 

 opinion that their labours concern the sciences of pure observa- 

 tion^ we ought to notice the part played by experiment in these 

 same labours, not only because our subject demands it, but for 

 the purpose of justifying the opinion we before advanced (Jour- 

 nal des Savants^ December 1840, p. 714) as to the real exist- 

 ence of only two classes of sciences, the sciences of pure reason- 

 ing and the sciences of reasoning, observation, and experiment. 

 When naturalists, having attained the object of their researches, 

 give perfect descriptions of the species they have examined, 

 their work is then founded upon that tohich is based on experi- 

 tne?it. The accuracy of descriptions depends on this, that they 

 relate to species perfectly defined in the mind of the observer 

 in consequoice oj the certainty he possesses of studying them in 

 a series of identical individuals issuing from successive genera- 

 tions ; now if he ivere ignorant of the fact of these successive ge- 

 nerations of identical beings^ this fact had no less precisio?i for 

 him than if it had been the residt of his oion experience ; this 

 proposition is evident on the least reflection. Every time on the 

 contrary that the true experimental basis, of which we are 

 speaking, is wanting to the naturalist in conseqvience of his ob- 

 serving for the first time one or two individuals of a species 

 foreign to his country, he is exposed to error, because he is apt 

 to take that for a species which is only a variety, or some young 

 or old individual of a species already known ; or if the indivi- 

 duals before him are really new, he gives as essential specific 

 characters, tliose which are exclusively peculiar to themselves. 



Second thing. 



Setting out with the observation of the diflTerences which dis- 

 tinguish the individuals of one and the same species from each 

 other, or the individuals of sub-species from different races 

 sprung from the same male and female, we are naturally led to 

 the study of the second thing comj^rised in our definition of 

 species ; and here comes the question whether circumstances very 

 different from those which now exist, could formerly have exer- 

 cised an influence on all, or at least some organized beings, so 

 powerful that they then might have constituted species entirely 

 different from those which the same beings represent now. 



At first sight, and looking only at the great modifications 

 which such species as the dog have undergone, antl Avhich have 

 aflTorded such diflPerent races as greyhounds, bulldogs, and spa- 

 niels, we are, it must be confessed, tempted to answer the fore- 

 going question in the affirmative, and to add that this answer, 

 which leads us to admit only one creation of organized beings, 

 by its simplicity satisfies many more people than are satisfied by 



VOL. VI, F 



