596 Prof. H. E. Armstrong and Dr. E. F. Armstrong. [Apr. 29, 



distilled water during 15 minutes were carefully dried between paper and 

 weighed ; they were then one-half to two-thirds immersed in solutions of the 

 substances tested — control leaves being immersed in distilled water vmder 

 similar conditions. After the required period these leaves were removed, 

 dried as before and weighed. 



The results obtained are collected in the following table : — 



Treatment. 



Increase in weight. 



18 hours in water 



24 „ „ 



18 ,, in chloroform water 



24 „ „ „ 



72 ,, in a solution of oarbon dioxide made from 



marble and acid 

 72 in a solution of carbon dioxide taken from 



a " sparklet" bottle 



72 „ in 3 per cent, sodium fluoride 



48 „ in 2 ,, „ chloride 



72 „ in 2 „ „ „- 



72 „ in water saturated with coal gas 



Per cent. 

 4-6 

 5 -0 

 19 -6 

 17 -0 

 12 1 



11 -5 



11 -1 

 2-0 

 2-8 

 4-9 



Obviously water enters freely only when active substances are present. 

 The appearance of the leaf indicated when water had entered, the veins being 

 swollen. Hydrogen cyanide was liberated only from leaves immersed in 

 chloroform, carbon dioxide and sodium fluoride. 



More concentrated solutions of sodium chloride have the contrary effect 

 and withdraw water from the leaf. Thus a leaf immersed during 24 hours at 

 the ordinary temperature in a 10-per-cent. solution weighed 2'098 grammes 

 before and 2-077 grammes after treatment, corresponding to a loss of 1 per 

 cent. Hydrogen cyanide was evolved but the leaf remained green. 



When leaves are stimulated, not only is hydrogen cyanide liberated and more 

 or less water absorbed but the amount of " reducing sugar" in the leaf is also 

 increased, owing to the ])reakdown of the glucoside and of other hydrolytes 

 Huch as cane sugar. To estimate this change the leaf was cut into small pieces, 

 quickly weighed and extracted with successive small quantities of boiling 

 water so as to put all enzymes out of action as rapidly as possible. Dextrose 

 was estimated gravimetrically in the aqueous extract. 



The amount of reducing sugar in fresh laurel loaves was determined at 

 fre(|uent intervals during the experinuuits ; it vai ied from 3 to per 

 cent. The following figures show the alteration produced by ana;stlietics : — 



