56 BIOLOGY OF PLANTS. 



tary branches, containing the elements of independent exist- 

 ence. Some of them fall off, as in several kinds of lily, and 

 take root, and form a new plant, while others remain attach- 

 ed to the stem or root. 



Although all plants seem capable of being propagated by 

 eyes, only a few are actually produced in this way. The po- 

 tato and the vine are almost the only examples of the use of 

 eyes for this purpose, unless propagation by slips, by budding 

 and grafting, may come under this designation. 



The development of vitality in the potato root is similar to 

 that of the seed. The eye corresponds to the germ, and the 

 bulb to the lobes of the seed. The matter necessary to sup- 

 ply the shoot with food, is treasured up in the bulb, just as that 

 is in the seed lobes which nourishes the germ of the seed. 



An eye from a branch of the vine being cut off with a small 

 portion of the wood, and placed under the same conditions 

 with the seed or bulb, will soon throw out roots and branches. 

 The wood furnishes the nourishment required, before it can 

 derive it from the soil ; for if the eye has no wood attached to 

 it, life will not be supported, and it will die. Other plants 

 may be propagated in this way, but the buds and bulbs of most 

 plants possess too little vitality to be successfully employed for 

 this purpose. Many plants, however, may be easily propaga- 

 ted by small branches, called 



Cuttings. When these are subjected to the proper condi- 

 tions of temperature and moisture, their buds give rise to new 

 individuals, capable of maintaining a separate existence. 



Propagation hy layers is the same as the above, witli this 

 difference. A layer is a branch bent into the earth and half 

 cut through at the bend. When this has thrown out roots in- 

 to the soil, it may be separated from the tree. The Ficus 

 Indicus, in its natural state, propagates itself in this way. 



Suckers are also employed for the propagation of plants. 

 They are sprouts sent up from the roots of trees and shrubs, 

 and make their appearance most frequently when the tree is 



