92 



D. T. MacDOUGAL 



The foregoing tests were made with sections in a hving condi- 

 tion in which questions of permeability and osmotic action 



Fig. 1. The use of the improved model of auxograph in measurement of swell- 

 ing of sections of plants and of biocoUoids. 



might possibly play a part. Material was prepared to exclude 



.the action of the living cell. The chlorophyllous layers were 



removed from the two sides of joints of Opuntia and slices, 7 



