THE SELF-FERTILIZATION OF PLANTS. 393 



character, will be generally, the most liable to ste- 

 rility, inter se. 



Agriculturists, and horticulturists, with Plants, and 

 breeders, and fanciers, with animals, may count confi- 

 dently upon an individual being susceptible of improve- 

 ment, or of increase in structure, whenever such indi- 

 vidual suffers any loss of vigor or fertility when self- 

 fertilized, or when closely interbred. The margin of 

 improvement, still possible, will be susceptible of ascer- 

 tainment, by noting the degree of the evil resulting from 

 (say) the animal mating with one of its own kind ; or, if 

 it be a plant, from the degree of evil resulting from 

 its self-impregnation. If it be a plant, and it be self- 

 impotent, it will ever be found, either that it has many 

 organs, in a rudimentary condition; or, that some one 

 organ has become extraordinarily dominant. In esti- 

 mating, however, whether a plant with perfect, or but 

 little impaired fertility, is fully and proportionately de- 

 veloped, or nearly so, security must be had against 

 such possible crossing with other varieties, or with 

 other individuals, as may be effected through the 

 agency of bees, and other insects. If, however, there 

 are no varieties, or individuals of the same species, 

 which have any positive differences distinguishing 

 them from the given individual, it may be safely con- 

 cluded, that the full fertility and vigor of the individual, 

 truly imply its full and proportionate development; 

 for, if those varieties, with which it is possible for it to 

 cross, have no points of structure, other than those 

 also possessed by the individual in question ; it is clear, 



that the fertility cannot be due to crossing. There is 

 34 



