MULTIPLICATION. 83 



ingredients necessary for the nutrition of the young 

 potato plants. The " eyes " of the potato are really 

 buds, as any one may see for himself who will examine 

 the "chits" of a sprouting potato. These latter bear 

 the same relation to the parent tuber that the shoots 

 which spring from the old "stools " in a coppice or from 

 a pollard willow do to the trunk. The presence of these 

 tubers indicates that, under natural circumstances, the 

 plant requires a long period of rest. To this end food is 

 stored in the tuber, and active growth ceases for a time, 

 until again excited by heat and moisture. It may be 

 inferred from this that continuous growth, were it possi- 

 ble, would be injurious because the climatal conditions 

 are unsuited for it, as, indeed, may be witnessed in the 

 way in which the haulms of the early potatoes are injured 

 by spring frost. 



Fertilization* In the case of plants grown for their 

 fruit or seed, as in the case of wheat and cereals generally, 

 much attention has naturally to be paid to the conditions 

 which favor sexual multiplication. 



The morphological characters of the plants undergo a 

 change. In general terms, it may be said that the growth 

 of the stem is arrested, and the growth and mode of de- 

 velopment of the leaves not only arrested, but more or 

 less profoundly modified, so as to form the parts of the 

 flower. All parts of the flower are constructed on the 

 same original plan as leaves, but they gradually assume a 

 very different appearance in the course of their develop- 

 ment to fit them for their work of aiding fertilization. 

 It is not necessary in this place to enter into details as to 

 the floral construction, which varies in different plants ; 

 the important points in relation to our present subject 

 are the stamens and the pistils and their contents. 



Within the green scales which constitute the flower of 



