236 M. Ch. Naudin on Hyhridity in Plants, 



cliaracters common to different groups ; and, lastly^ The 

 perpetuation of resemblances between the. individuals of the 

 same group constitute the elements of species. Species 

 contain nothing more or less. 



It is not, therefore, an ideal type, as certain abstract- 

 loving naturalists have suggested ; it is essentially a collec- 

 tion of similar individuals. The abstract ideal type of a 

 common organisation is only, as it were, a tie, which in 

 our mind collects similar individuals in the same bundle, 

 and sums up the contrasts (or differences) which separate 

 their group from every other. 



It is necessary, then, to return to the pure and simple 

 definition of Cuvier, — viz., A species is a collection of indi- 

 viduals descended from one another^ or from common parents^ 

 and from those tvJiich resemble them as much as they resemble 

 themselves. 



Let us remark, in passing, that in thus defining species, 

 Cuvier did not take races and varieties into consideration. 



Everywhere where there is a group of similar individuals, 

 contrasting in some measure with other groups, and pre - 

 serving through a series of generations the physiognomy 

 and organisation common to all the individuals, — there is a 

 species. 



It is by their contrast that species are distinguished from 

 one another, and it is by comparison that their contrasts 

 appear. Contrasts may be more or less great according to 

 the objects compared. If they are very great and well 

 marked, all the world acknowlege the specific distinction 

 of the compared forms ; if they are very weak, almost in- 

 appreciable, opinions are divided ; one party separating the 

 feebly contrasting forms into distinct specific groups, the 

 other collecting them into one, and applying to them in the 

 mean time the qualifications of races or varieties. 



These collections and separations are purely optional, and 

 they can have no other rule than scientific or economic ad- 

 vantage ; in order to determine them it is necessary to be 

 endowed with a certain tact which is ordinarily acquired by 

 experience. 



In short, there is no qualitative difference between 

 species, races, and varieties ; it is idle to seek one. These- 



