176 The Origin of Species by Mutation. 



of many species the individuals differ according to the 

 region which they inhabit, and that by means of these 

 differences the species can be spht up into local races. 

 The differences may be very slight and often only vis- 

 ible to the initiated, and yet perfectly (Constant. But 

 these facts are far from being appreciated as much as 

 they deserve.-^ 



§ 23. SPECIES IN CULTIVATION. 



Just as wild species at present consist of a larger or 

 smaller number of constant and independent subspecies, 

 so presumably will it have been with those species which 

 man has brought into cultivation. 



Pliny was acquainted with the different kinds of a 

 number of fruit trees, for example 43 sorts of pears, 

 29 of apples, 10 of plums, 8 of cherries and so forth. 

 The Romans knew at least two sorts of beet, several 

 kinds of which grow wild in the Mediterranean region. 



In about the year 1600 Olivier de Serres described 

 in his Theatre d' agriculture the cultivated plants that 

 were known at that time. He refers also to the main 

 types of our modern vegetables. He mentions 61 vari- 

 eties of pears, and 51 of apples, and also the commonly 

 grown sorts of beet. Whence all these forms arose we 

 do not know. It is possible that they arose in cultiva- 

 tion; it is even possible that they arose as the result of 

 cultivation. But it is equally possible that they existed be- 

 fore it, growing wild either together or in different places, 

 and that all or most of them were taken over into culti- 

 vation as such. For there is absolutely no ground for 

 the belief that the plants known to agriculture were only 



^ See also Duncker, Roux's Archiv, Vol. VIII, 1899, P- 164. 



