WlNIFKEl> K. HhEXCHLEV 



219 



(1) ].s/ period from the scedliug stage till the time that the plant re- 

 gains its initial weight after the loss by respiration — i.e. the time during 

 which a casual observer would say that the plant "makes no growth." 



(2) "Ind 'period, succeeding the former, during most of which the 

 plant is obviously making growth, and which continues to the end of 

 the experiment. 



1.9^ period of grotvlh. 



In the division of the plant into root and shoot the remains of the 

 seed are associated with the shoot. From the very first the root increases 

 steadily, though slowly, in weight even while the total weight of the 

 plant is diminishing. This increased root substance is therefore obtained 

 at first at the expense of the shoot and must consist of material trans- 

 ferred from the seed or of the earlier products of assimilation or possibly 



grams 

 15 



10 

 seeds- 



_._!-, _|-.-i— — r' " i" 



Whole 

 ^ plant 



Deo. 2 Jan. 6 Feb. 3 Mar. 2 



Fig. 5. Winter Groirtli. Dry weights of 10 pea plants, series E, grown from 

 Dec. 2nd, 1915 — March 9th, 1916. Nutrient sohitions changed weekly. 



of both. As the root thus increases in weight all the time, the loss of 

 weight in the whole plant is less marked than in the shoot alone, and it 

 therefore happens that the whole plant regains the initial seedling weight 

 earlier than the shoot does. The length of time taken by the shoot to 

 pass through the first period of growth varied with the time of year 

 according to the prevailing temperatures as follows: 



