g6 HYBRIDISING AND CROSS-BREEDING. 



cultivation, the plant becomes changed, and its offspring are 

 likely to vary. Culture is one disturbing influence ; but culti- 

 vators avail themselves of even more violent measures in con- 

 junction with it, one of the most potent of these being hybridi- 

 sation. That plants are changed and ameliorated by culture 

 has been known from the beginning of man's history ; indeed, 

 culture is especially used as a means of increasing crops, or 

 with the definite object of changing them in size, form, texture, 

 flavour, and value, either as necessaries or luxuries. 



Wichura has the following remarks on the subject of cultural 

 variability : " Transported from nature into the garden, or from 

 a warm into a colder climate, the plant preserves its peculiari- 

 ties for a time ; then slight changes creep in, and more follow, 

 until ultimately, by repeated generation, scarcely one seedling 

 individual is like another. In this state the pollen of many 

 plants resembles that of hybrids in its variability of form, 

 structure, and even chemical composition. Most cultivated 

 varieties of Primula auricula, Hyacinthus oriejitalis, Tulipa 

 gesneriana, Solatium tuber osum, Brassica oleracea, Mathiola 

 incana, Antirrhinum majus, Cineraria cruenta, and Verbenas, 

 have strikingly irregular pollen. Koelreuter therefore says rightly 

 that the nature of species of plants and beasts is to a certain 

 extent like that of hybrids as soon as they are in any way re- 

 moved from their natural conditions. Where culture and 

 hybridising or cross-breeding concur, the consequences of dis- 

 accommodation are naturally quicker and more extensive or 

 variable than where only one of these agencies is at work. 

 Thus we find in fancy and show Pelargoniums, giant Pansies, 

 Calceolarias, Fuchsias, Strawberries, and many other artificial 

 or hybrid races, variability and multiformity of pollen in the 

 highest degree. It is probable, although not proven, that in 

 cultivated plants that is, species as in hybrids irregularity of 

 pollen favours variability. If gardeners, in raising new fruits 

 or flowers, varieties or hybrids, would use the microscope or a 

 good lens, and allow those individuals to remain for seed which 

 have the most irregular pollen, or if they would use the most 

 irregular pollen in artificial fertilisation, they would doubtless 

 materially facilitate the accomplishment of their desires. The 

 imperfection of pollen in hybrids is often adduced as a decid- 

 edly distinctive mark between them and pure species ; but the 

 fact is, there are hybrids the pollen of which is little less regular 

 than that of the parents as, for example, in Petunias; and 

 there are pure species, or wild plants regarded as such, which 

 have more irregular pollen than many known hybrids. Yet, 

 generally speaking, it is quite true that hybrids generally have 



