260 



BOTANICAL GAZETTE 



[OCTOBER 



of the eighth pair after three days, but none in the leaf of the 

 ninth pair. After five days the cooled zone was gradually brought 

 to room temperature and the coil removed. Fig. 3 shows the con- 

 dition of the plant twelve days after the beginning of the experi- 

 ment. The experimental leaf is the member on the left of the 

 figure of the pair showing bud development. In this and the 

 opposite leaf all buds which were submerged show vigorous out- 

 growth. In the leaf of the ninth pair ten buds out of twelve sub- 

 merged developed, but only three of these produced distinct shoots, 



and all are much retarded 

 k as compared with those of 



the leaves above. Fig. 3 

 does not show the roots 

 on this leaf, since they 

 are on the under side. 

 Series 44, March 30, 

 —Temperature of 

 3-4 C. on petiole of one 

 leaf (A) of seventh pair 

 below tip. Opposite leaf 

 {B) and both leaves (C 

 and D) of sixth pair in 

 water. The leaf D was in 



1919. 



o 



Fig. 3 



xperiment 



ing that time showed no development of buds. After seven days 



the coil removed. 



gradually 



experimental 



ten notches, B in two notches, C in none, and D in five notches. 

 During the following week three days of high temperature in the 

 greenhouse occurred, and this may have aided the development of 

 some further buds. The condition of the four leaves eighteen days 



;inning of the experiment 



In A 



every bud submerged has developed; in B nine buds out of four- 

 teen submerged have developed, but only three of them have gone 

 beyond the earliest stages ; in C eight buds out of sixteen submerged 

 show some development, but all except two have been inhibited in 

 early stages; in D four buds out of fifteen submerged have developed 



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