EXPERIMENTS IN ALASKA. 95 



The President — Dr. Hansen, in your investigations, have you looked 

 into it at all, the effect of a long day upon vegetation? 



Dr. Hansen — As near as we can get at it, that is what saves time. 

 In the long interior, the midnight sun is only for a short time, so that the 

 plants do get a certain amount of rest during most of the growing season. 



The President — It involves the question of the necessity of rest 

 for plants, whether there is anything in it — do plants require rest? 



Dr. Britton — We think the matter to be determined accurately, 

 would have to be taken up in some such region as that spoken of by 

 Dr. Evans. Of course, we could not determine that experimentally, ex- 

 cept under the natural conditions. It would be impossible to attempt it 

 anywhere else. So far as I know, there is no information on it. 



The President— Odn you give us the statement in regard to the 

 period of twenty- four hours in which plants make their greatest growth? 



Dr. Britton — I cannot tell you that. 



The President — We will now ask Mr. Hays to read his paper. 



