MUTUAL CONNECTIONS OF PLANTS. 97 



The case is similar with respect to the Crossing of Species. 

 By this we understand such changes as arise from the mutual 

 impregnation of two related species. It cannot be denied 

 a kind of bastards are thus produced: they are called /w/- 

 brid pla/nts (plantte hyhridte). They occur most common- 

 ly among plants which are cultivated. Thus, in the ge- 

 nus Pyrus, Prunus^ as also among the species of Grain, and 

 in the kitchen vegetables, there are a considerable number of 

 real hybrids, which do not lose their properties even by re- 

 production. But most of these plants are productions of art, 

 and Nature seems to prevent the mutual impregnation of re- 

 lated species in more ways than one, although these are not 

 completely understood by us, (332.) 



r 



145. 



All properties of plants which are subject to change, form 

 either a Subspecies {subspecies), or a Vai'iety {varietas). By 

 the former we understand such forms as continue indeed 

 during some reproductions, but at last, by a greater difference 

 of soil, of climate, and of treatment, are either lost or changed. 

 When the different Cabbage species receive the same treat- 

 ment in the same climate, they continue to be frequently re- 

 produced, without changing their appearance. But we can- 

 not on this account maintain, that Cauliflower would retain 

 the same favourite form in very different climates, and under 

 a complete change of treatment. It at last changes so much, 

 that it can scarcely be distinguished from the Common Cab- 

 bage. This, therefore, is a subspecies. Varieties again do 

 not retain their forms during reproduction. The variable 

 colours, — the very variable taste, and other properties of the 

 kitchen vegetables, the ornamental plants, and the fruit-trees, 

 shew what varieties are ; and the Scientific Botanist must there- 

 fore be particularly attentive to distinguish permanent species 

 from the variable subspecies, degenerate plants, and varieties. 



146. 



To this discrimination belongs, above all things, a careful, 

 continued, and unprejudiced observation of the whole vegeta- 



