462 INTRODUCTORY LECTURES. 



adopted Classes and Orders, the character of these must always 

 enter as a part of the character of the genus. Sometimes I have 

 left it out, at other times I have inserted in the character of the 

 genus that of the class or order. 



Every species ought to have the character of its genus ; and 

 in naming or distinguishing species in Nosology or in Botany, it 

 is supposed sufficient merely to name the genus, and to add such 

 marks as distinguish the species. Take this remark, however, 

 that in Botany as well as in Nosology, though the character of 

 the genus is always supposed to be in the species, yet every part 

 of the character of the genus is not always in the species. As 

 an example from Botany, I may mention the Ranunculus, which 

 stands in the class Polyandria : one species of Ranunculus, how- 

 ever, the R. hederacea, never has more than five stamina, and 

 ought therefore to have belonged to the class Pentandria ; but 

 the generic character of Ranunculus does not solely depend up- 

 on the number of stamina, but upon many other particulars, 

 all of which occur in this species. If, accordingly, the character 

 of a genus consists of five parts, and any given plant contains 

 four out of the five, the want of the fifth does not separate it 

 from the genus which it most resembles. Nor will the want of a 

 single part of the character in the definition of a disease separate 

 one individual from a species ; it may happen that in a case of 

 jaundice the " faeces albae" may be wanting, yet if the yellow 

 colour of the face and eyes, and certain circumstances about the 

 precordia, are present, there will be no doubt that the case is 

 jaundice. 



After these remarks, I must add, that nosologists and other 

 systematists have in view two things, viz. Distinction and De- 

 nomination ; that is, a part of the methodical system consists 

 in affixing proper terms to the distinctions established. This 

 last part is hardly less necessary than the other, as we, by ap- 

 plying fixed terms, in a manner realize our distinctions, and give 

 precision to our ideas. I can refer you to very full information 

 on this subject in the Philosophies Botanica of Linnaeus ; for 

 what he says as to the appellation of plants will apply to every 

 other department of science, and in particular to Nosology. 

 And it is the less necessary to insist on this subject, because, 

 in the attempt I have made towards a method, I have nowhere 



