446 . BOTANICAL GAZETTE [DECEMBER 
PERCENTAGE BOUND WATER . 
ss ‘ 
| 
s 
rt 
NOILVYLNIINOD JDVINIINAd 
4 
. op ° 9 
LOG |BOUND WATER 
to 
40 
NOILVULNIINOD DOT 
70 
80 
oe 1.—Relation between concentration 
gum acacia sols and water bound by the ie. 
Division oF AGRICULTURAL mbes our 
UnNIvErsiry oF MINNESOT. 
in solution is fairly well 
known; (4) its effect on the 
swelling of colloids is prob- 
ably negligible. In objection 
it may be stated that plant 
been followed of grinding 
the sucrose to a fine powder 
which dissolves rapidly with 
shaking, and the sap has been 
maintained continuously at 
low temperature. Under 
these conditions no increased 
depression of the freezing 
point which could be attri- 
buted to invertase action has 
been observed in a somewhat 
extended series of determi- 
nations on the same sample. 
Conditions of equilibrium, 
-and possible errors due to 
adsorption of the sugar by 
colloids, have not yet been 
investigated. The data 
already secured, however, ap- 
pear to justify the proposal 
of the method for the esti- . 
mation of the relative (not 
absolute) content of hydro- 
philic colloids in expressed 
plant tissue fluids. Itseems 
probable that the method 
may be applied also to other 
biological fluids. 
