362 MacDOUGAL— HYDRATION AND GROWTH. 



A section of a similar branch about 8 mm. in thickness and 42 

 cm. long was cut away from another basal branch of the tree, the 

 end of the detached portion quickly sealed with vaseline and when 

 all was in readiness the tip was excised and the cut thrust into 

 water to ascertain the actual deficiency in this portion. 14 hours 

 later a total of 6 c.c. of water had been absorbed and 24 hours later 

 8.5 c.c, which was a practical saturation, at a temperature of 18° 

 to 20° C. The volume of the branch proved to be 35 c.c. so that the 

 amount of water absorbed was 24 per cent, of the total. 



Sections of young internodes of Jnglans calif ornica qucrcina 

 which had an average diameter of about 2.5 mm. were swelled in 

 solutions as below, then dried and swelled again with results as 

 below at 16° C. 



Water. Citric Acid o.oi Normal. Potass. Hydrate o.oi M. Potass. Nitrate o.oi M. 



Fresh — living. 

 10% 14% 13.2% 12% 



After Drying. 

 34 34 34 32 



(On basis of original thickness.) 



The unsatisfied capacity of these sections taken from young ter- 

 minal internodes was comparatively great, doubtless due in part to 

 the constant drain of the active leaves they bore. The older wood 

 including that formed the previous year showed an absorptive 

 capacity of 22 per cent, in water. Now it is from these older inter- 

 nodes that the nuts arise. 



The nuts were highly turgid, exuded sap when cut into, and 

 hence must have had a colloidal composition which acted to with- 

 draw water from the stems which contained a much lower percentage 

 of water. The soil w^as low in moisture content at this time, as it 

 had been four to five months since the rains. 



Tests of nuts 8 to 10 mm. in thickness from which tangential 

 slices had been removed to give a uniform thickness of 7.5 mm. 

 were made in July, and these swelled at temperature of 17 to 30° C. 

 in solutions as follows : 



Distilled Water. Citric Acid, .01 Af. Potass. Hydrate, .01 Af. Potass. Nitrate, .oiAf. 



1.5% 1.8% 1.4% 2% 



