Winifred E. Brenchley 



231 



It is difficult to suggest an explanation as to why the abrupt changes 

 followed by a period of steady growth should be the rule, instead of a 

 gradual decrease in growth parallel with the gradual decrease in food. 

 A comparison of these series (Figs. 9 and 10), with the corresponding 

 sets with unlimited food supply (Figs. 4 and 5), shows that except during 



grams 

 15 



Whole 

 plant 



5 

 10 

 leed*-*- 



Deo. 4 Jan. 7 Feb. 4 Mar. 3 



Fig. 9. Winter Growth. Dry weights of 10 pea plants, series F, grown from 



Dec. 4th, 1915 — March 10th. 1916. Nutrient solutions never changed. 



grams 

 25 



Whole 

 plant 



Shoot, 

 with 

 pods 



Shoot, 

 ithout 

 pods 



Apr. 26 May 3 June 7 July 5 



Fig. 10. Summer droicth. Dry weight of 10 pea plants, series N, grown from 

 April 'ieth — July l'2th, 1916. Nutrient solutions never changed. 



the summer period of very rapid growth the amount of dry matter 

 produced with limited and unlimited food supply is much the same or 

 even identical for several weeks after the end of the first period, showing 

 that the gradual reduction in food material does not always immediately 

 affect growth. Eventually the well-supplied plants continue their steady 



