CHAPTER XII. 



VEGETATIVE PROPAGATION. 



IN the life of any organism there are two chief phases, which are not 

 always distinct from one another, and may overlap. The one secures 

 the maintenance of the individual, the 

 other increases the number of indivi- 

 duals. Thus far the former only has 

 been followed. It has been seen how 

 the Plant is established on germination, 

 and developed as an organism which 

 can maintain itself. It is able, more- 

 over, to acquire material in excess of 

 its immediate needs. This is in itself 

 a necessary condition of increase in 

 number, for there must be at least a 

 sufficiency of material for forming the 

 new germ or germs. But it is not 

 possible to put any measure on the 

 amount of material required to be at 

 hand before increase takes place. An 

 unusually early propagation in a Seed- 

 Plant is seen in the Potato, where 

 the seedling may form a tuber from 

 the axillary bud of each cotyledon 

 (Fig. 159). 



There are two methods of increase. 

 One is by Vegetative Propagation, which consists simply in separation 

 of a part of the plant-body as a being physiologically independent of 

 the parent. During its early development that part is nourished by 

 the parent. The separation may finally be completed by the death 



FIG. 159. 



Seedling of the Potato, showing how 

 the buds (ax) in axils ot the coty- 

 ledons (c) develop as tubers. (After 

 Percival.) 



