216 Mr. Bicheno on Systems and Methods 



volve in inextricable difficulty all our well known species, make 

 us dependent upon empirical and traditional evidence for our 

 acquaintance with them, and render it impossible to derive in- 

 struction from books. In such cases the assumed law ought 

 to be brought to the test of experiment, or the species should 

 be rejected. 



Many of our cultivated plants also tend to invalidate the 

 law. Who can refer our cerealia and esculent vegetables, in 

 many instances, to their true types ? and how few of our old 

 flowers are there, of which the astutest botanist can trace the 

 origin ! Domesticated animals afford a still more striking 

 example ; and man himself furnishes the most difficult pro- 

 blem of all. 



These remarks and examples are, I apprehend, sufficient to 

 show how difficult it is to adopt the term in its strict accepta- 

 tion ; and that however precisely the naturalist has attempted 

 to employ it, he has not succeeded to the extent he has pro- 

 posed ; and that it can only be taken as correct in a vague 

 and general sense, and as a convenient abstraction to relieve 

 him at the first step from the necessity of becoming acquainted 

 with every individual. 



The next term of importance to the naturalist upon which 

 the accuracy of his reasoning depends, is that division of his 

 system which he denominates a Genus, This is an assemblage 

 of individuals agreeing also in some common characters ; but, 

 unlike the word species, it is not previously defined. Thus 

 much indeed has been thought requisite; that in botany these 

 common characters should be taken from the parts of fructi- 

 fication, and in zoology from such parts as are indicative of 

 structure and habits. " A genus should furnish a character, 

 not a character form a genus." We are not here, as in the 

 word species, precluded from inquiry by a previous definition. 

 Though both words are terms of generalization, there is the 

 same difference between them, as instruments of reasoning, as 

 between a definition and a proposition in geometry. 



The species includes all the characters which are in the 

 genus, and those likewise which distinguish that species from 

 others belonging to the same genus ; and the more divisions 

 we make, as order, family, class, it is intended that the names 

 of the lower should become still the more comprehensive in 

 their signification, but the less extensive in their application 

 to individuals. Naturalists by this invention, which is not 

 exclusively their own, have it in their power to contemplate 

 and reason upon these separate characters, with all their conse- 

 quences, as if they existed independently of species ; as by the 

 use of the word species they are enabled to look at their pe- 

 culiar 



