82 massachusetts horticultural society. 



Plant Response to Other Factors than Anesthetics and 

 Toxic Substances. 



Under one of the preceding di\isions of this paper the writer 

 has already referred to plant responses due to other agencies than 

 those produced by anesthetic or toxic substances. A further 

 consideration of these substances seems essential to a fuller con- 

 ception of the rdle played by each of these influences in imparting 

 a growth impulse to the plant. We have previously noted that 

 immersion in hot water for a certain period of time proved more 

 effective than ether in accelerating growth. Our own exjDcriments 

 with vacuum treated astilbe have shown gains of from four to ten 

 days, as compared with six to eleven days for ether-treated plants. 

 Howard (12) in the winter of 1905-06, in connection with some 

 rather extensive experimental investigations regarding the winter 

 rest period of deciduous trees and shrubs, studied the comparative 

 effect of ether, frost, partial dessication, and storage in a dark 

 closet at a rather high temperature and in a nearly moisture satu- 

 rated air. The results of this comparative test with seventy species 

 of plants are summed up in Table III. 



The data shows that while etherized plants were accelerated 

 nearly 9.8 days those dried for five days showed a gain of 9.4 days. 

 The frozen plants were 4.3 days earlier than the control plants, 

 while those subjected to darkness, moisture, and a high temperature 

 showed a slight retardation. Another effect of the treatment noted 

 by Howard was wuth respect to the percentage of buds that opened. 

 Plants etherized 48 hrs. opened 50% of their buds as against 

 44.2% on the control plants. Those etherized 72 hrs. only opened 

 35.7%. Plants dried one day opened 45.7% while those dried 

 five days only opened 32.8%. Plants frozen eight days opened 

 34.2% while those frozen fourteen days opened 32.8% of their buds. 



It is evident from this analysis that there are two distinct effects 

 of treatment, that which imparts a certain amount of growth 

 impulse to some buds, and that which exerts an injurious influence 

 upon others. The severer treatments gave on the average the 

 greatest growth acceleration and the smallest percentage of buds 

 opened. 



