THE CLASSIFICATION OF PLANTS. 397 



There is not the slightest foundation for the theory, which has been 

 advocated by some naturalists, of a transmutation of species. 

 All such statements therefore, that have been made, of the 

 conversion of Oats into Rye, or of any species whatever into 

 another, are entirely without foundation, and have arisen from 

 imperfect observation. A case, showing the importance of care- 

 fully investigating such supposed transmutations, has been 

 recorded in the Gardener's Chronicle for October 6, 1849. A 

 spikelet of Oats was seen to come out from a head of Wheat. 

 On examination it appeared that the stalk of the Oat had twisted 

 itself round the ear of \A''heat Avhen both were ver^^ young, and 

 they had grown up together in close apposition, the chaff of the 

 Wheat completely hiding the stalk of the Oat, which was at 

 last, by some accident or violence, snapped from its parent and 

 left clinging to its supporter, all trace of its origin being 

 hidden. 



In practice it is very important that we should distinguish all 

 the above varieties from true species, for nothing is so calculated 

 to lead to confusion in descriptive botany as the raising of mere 

 varieties to the condition of species. No individuals should be 

 considered as constituting a species unless they exhibit important 

 and permanent distinctive characters in a wild state, and which 

 can be perpetuated by seed. Great uncertainty still prevails in 

 our systematic Avorks as to what is a species and what is a 

 variety; and hence we find different authors, who have written 

 on British and other plants, estimate the number of species con- 

 tained in such genera as Eosa, Rubus, Saxifraga, Hieracium, 

 Sahx, Smilax, &c., very differently. 



2. Genera. — The most superficial observer of plants will have 

 noticed that, certain species are more nearly allied to each other 

 than to other species. Thus, the difierent kinds of Roses, 

 Brambles, Heaths, Willows, may be cited as familiar examples 

 of such assemblages of species ; for, although the plants com- 

 prehended under these names present certain well-marked dis- 

 tinctive characters, yet there are at the same time also, striking 

 resemblances between them. Such assemblages of species are 

 called genera. A genus, therefore, is a collection of species 

 which resemble one another in general structure and appearance 

 more than they resemble any other species. Thus, the various 

 kinds of Brambles constitute one genus, the Roses another, the 

 Willows, Heaths, Clovers, Oaks, &c.,form also, in hke manner, as 

 many different genera. The characters of a genus are taken 

 exclusively from the organs of reproduction, while those of a 

 species are derived generally from all parts of the plant. Hence 

 a genus might be defined as a collection of species which re- 

 evidence be adduced, adhere to the views above expressed, as 

 to the nature of species and varieties. 



