412 



BOTANICAL GAZETTE 



MAY 



about 0.2 mm. and these gave swellings at i6° C. which are to be 

 compared with the swellings of fresh material. 



The second swelling produced an expansion scarcely more than 

 half that of the first in all solutions, and being still further decreased 

 in alkali, furnishing striking parallels with the action of succulent 

 leaves of Castilleja. 



TABLE VII 



TABLE VIII 



Hydration reactions of succulent and thin leaves of Castilleja; 



JULY 28-31; at 16° c. 



Two additional treatments of the leaves were given to test the 

 effects of hydration on the swelling capacity of the contained 

 colloids. In one case the trios of sections which had swelled were 

 dried on filter paper for a day at 20° C, with only enough pressure 

 to prevent warping or curling, then again hydrated in water or the 

 identical solutions of the first swelHng. The second case included 

 a swelling of leaves which had been simply dried for a day at 20° C, 

 in which process they came down to about half the original thick- 

 ness. The measurements at 17-18° C, calculated on dried thick- 

 ness, which was usually about one-half that of living material, are 

 given in table VIII. 



