CLASSIFICATION OF PLAN'J'S. 99 



causes. These differences appear to depend on the mode 

 of culture, richness of the soil, temperature of the climate, 

 influence of the pollen of one plant on the stigma of anoth- 

 er, &c. The changes thus produced, affect chiefly the mag- 

 nitude, color, or number of petals of the flowers, the form 

 of the leaves, the size, color, and taste of the fruit, and the 

 qualities or form of the roots. But the seed of the species 

 is never thus changed, always producing the original kind, 

 and not the peculiarity of that variety from which it was 

 taken. Thus the apple and pear produce innumerable varie- 

 ties, in respect to form, color, and taste, but the specie ;s of 

 each always remains the same. 



If several seeds from the same apple tree be planted, each 

 new tree thus produced, will probably bring forth fruit, which 

 not only differs from that of the parent tree, but also from 

 each other. Thus seeds from green sour apples, will pro- 

 duce sweet red fruit, or the contrary. And so the seeds 

 from large apples will produce, or may produce small fruit, 

 and in like manner, seeds from small apples may produce 

 large fruit. But though the apple and pear belong to the 

 same genus, that is, Pyrus, no human means can change 

 one into the other, that is, the seeds of the apple, though they 

 may produce varieties which differ greatly from each other, 

 never produce pears. 



In this respect, the law of nature is as immutable as it is 

 with respect to gravity, or to the rising and setting of the 

 sun. In no instance has a new species ever been known to 

 be produced by cultivation, mixture, or any other means. In 

 some instances, monsters, differing greatly in many respects 

 from the species, have been the product of art or intermix- 

 ture, but they seldom or never bear seeds which are prolific. 

 So that the established law of nature, though in appearance 

 thus encroached upon, is never broken, but rather in the sight 

 of man, confirmed by such products. 



Were it otherwise, and were new species formed by inter- 

 mixture, or by any other means, it is obvious that the face of 

 nature would constantly be subject to entire revolutions, and 

 that the trees of the forest, and the seed-bearing corn, as well 

 as the more humble grass of the field, which are the same 



What is meant by varieties ? What circumstances produce varieties? 

 What parts are chiefly affected in the formation of varieties '{ Are the 

 species ever changed by the circumstances which produce varieties ? . 

 Have the species of plants ever been known to be changed by any circura 



stance whatever '/ 



