August 12, 1898.] 



SCIENCE. 



187 



the genus to the emendator. Confusion also 

 attended this practice in that it soon became 

 difficult to ascertain the character and impor- 

 tance of the changes worked by successive stu- 

 dents, and opinions greatly differed as to the 

 merits of the various references, so that on the 

 ground of convenience merely there has been 

 an increasing tendency to credit the genus to its 

 original author, the inventor of the name, and 

 ignore the fact of subsequent emendation. This 

 is, then, a practical abandonment, for nomen- 

 clatorial reasons, of the custom of treating the 

 genus as a mental concept, and the purport of 

 the original description has come to be so far 

 ignored that the Rochester Code bases botanical 

 nomenclature on a work which contained no 

 definitions of genera, necessitating that all 

 knowledge of them be gained by inference from 

 the included species. 



But the above view as to the nature of genera 

 is as false in theory as it has proved impossible 

 in practice. Species, genus, family and order 

 are as actual and real as regiment, division and 

 corps or other collective nouns. It may not 

 be possible to define the terms to the satisfac- 

 tion of all, but for nomenclatorial purposes it is 

 quite sufiicient to know that a species is a 

 group of individuals, and a genus a group of 

 species. If we think of a species as an island 

 in the sea of extinction a genus is an archipel- 

 ago, a group of neighboring islands. There 

 being no biological latitude and longitude, we 

 are obliged to indicate the islands and the 

 group by describing them. The history of 

 geographical discovery has proved that it is not 

 easy to distinguish by description between nu- 

 merous similar islands, and systematic science 

 has in the last decades abandoned the descrip- 

 tion as the final resort for the interpretation of 

 the species and taken to the original specimen 

 or ' type.' It is still protested by the surviving 

 idealists that no single specimen can give an 

 adequate idea of the species, and nobody claims 

 that it can, but the desirability of a single 

 definite nexus between nature aud science is 

 rapidly becoming patent to all. A complete 

 description of a species can only be drawn after 

 it is known throughout its range aud variations, 

 and until its entire life-history has been ascer- 

 tained, but the preservation of a type specimen 



renders easy and definite the settlement of 

 questions which could in many cases never be 

 positively decided otherwise. The discoverers 

 of an island may reach it from different sides, 

 and may disagree in the accounts of what they 

 saw, but if their points of observation are known 

 later travelers can harmonize the discrepancies, 

 correct the errors and complete the descrip- 

 tion. 



The method of types is rapidly becoming uni- 

 versal in the study of species, but with respect 

 to genera the idealists are still much more in 

 evidence. The case is, however, exactly the 

 same. A genus being a group of species, it 

 is more satisfactory and final to know one 

 of the species than to hear any amount of 

 general remarks about the group as a whole, 

 especially|if the region has not been thoroughly 

 explored and mapped. The discoverer of a 

 new genus simply recognizes that a certain 

 species, or more, lies at a distance from any of 

 the groups which have been previously desig- 

 nated as genera. In a majority of cases he be- 

 comes aware of this fact through observation on 

 some single species, which he proceeds to de- 

 scribe and figure with special care. He may 

 not know the size, direction or extent of his 

 new archipelago ; all the general characters he 

 alleges as features of the group may fail in the 

 light of later study, and yet the fact would re- 

 main that he had first recognized as distinct 

 from all others that particular group of species. 

 As before, the genus cannot be truly defined, 

 the characters by which it is distinguishable 

 cannot be formulated, till all the species are 

 known. The characters might, indeed, long 

 elude us without impairing the distinctness of 

 the genus. The species and genus, in the real- 

 istic view, are in an important sense independent 

 of characters, the formal characters being the 

 means of pointing out the group, rather than 

 the primary ground of its existence. The de- 

 scription, whether by ancient or modern writer, 

 loses its sanctity and is distinctly subsidiary in 

 authority to the type. 



The idealistic theory having proved imprac- 

 ticable, the method of types is being rapidly 

 substituted, even without the recognition of a 

 logical base for its use. An objection is some- 

 times raised that as the early systematists did 



