232 



Physiological Pre-determination 



We may now consider for comparison witii the normal plant the 

 results obtained with plants from which different proportions of the 

 initial food-reserves had been removed. Curves 6 and c (in Figs. 1 and 2) 

 show that the removal of part of the initial food-reserves affects the 

 subsequent growth and yield of the plant in two distinct ways. In the 

 first place, broadly speaking the growth made by the plant, and conse- 

 quently its final yield, is aj)j>roximatelij proportional to the amount of 

 food-material originally present; this may be called the pre-determining 

 effect of the initial "capital." Secondly, the partial removal of the 

 food-reserves has a specific pre-determining effect upon the "rate of 

 interest," and it is in consequence of this fact that strict proportionality 

 between the experimental and the control plants is not maintained. 



The effect of loss of food-material upon the "rate of interest" is 

 brought out in Fig. 2. In the case of the removal of one cotyledon and 

 one foliage leaf the "rate of interest" is less than that of the control 

 during the first three weeks. Later it increases rapidly, surpasses, and 

 remains higher than that of the normal plant during the remainder of 

 the growth period. Where both cotyledons are removed, however, the 

 consequences are different. The "rate of interest" remains less than 

 that of the normal plant throughout the whole course of development. 

 l-o 



A = 



X h- 6 & 10 



l^^sCaCivc Qrouth Tkriod 

 Fig. 3. 

 Dry weight of the plantsfroin wiiicii one cotyledon and one foliage leaf iiad been I'oinoved 

 Dry weight of the normal plants. 

 Dry weight of the plants f rom which both cotyledons had been removed 

 ^Dry wcMght of the normal plants. 



B = 



