The Plantlet. 43 



and to recombine them into foods of various kinds which 

 can be used by the protoplasm in making new parts and 

 in repairing waste (Assimilation (as-sini'-i-la'-tion)). 

 Until this food preparation commences, no new plant sub- 

 stance has been formed. It is true that new cell -walls 

 and new protoplasm may be formed from the food sup- 

 ply of the seed before chlorophyll appears, but until 

 chlorophyll is formed, and food preparation begins, the 

 whole plantlet with whatever remains of the seed, when 

 dried, weighs no more than the seed weighed at the be- 

 ginning. The material formed for food is starch, or some 

 substance of similar composition (sugar or oil), which, 

 after undergoing chemical changes if need be, to render 

 it soluble, is distributed throughout the plant to be built 

 up into cell-walls and protoplasm, or to be held as reserve 

 food (14). * 



Food preparation and assimilation 

 are not necessarily simultaneous, but 

 either may proceed without the other. 

 Only plants can prepare food from 

 mineral substances. The food of ani- 

 mals must all have been first formed 

 by plants. 



60. The Sources of Plant Food. By 

 FIG. 16. showing observing plantlets of the bean or 



starch crystals stored as pumpkin a f ew days a f ter germina- 

 reserve food in a cell of J 



potato. Highly magni- nation, we may discover that the coty- 

 ledons, which were at first so plump, 

 have shriveled to a mere fraction of their former size. 

 This change is due to the fact that the food contained by 

 these parts has been absorbed by the developing plant- 

 let. The patrimony furnished by the seed is quickly ex- 



