356 BOTANICAL GAZETTE [APRIL 
including the white pulp within the spiny ridges, a being the outer 
sample taken from the area just under the cuticle, b being just 
interior to a, while c represents the great body of the deeper pulp 
and is characteristic of nine-tenths of the cortical tissue. The sugar 
analyses were made with Fehling’s solution, calculations being 
made in terms of dextrose. Reducing sugars were determined by 
direct titration of the neutralized sap, soluble non-reducing sugars 
similarly after one hour’s hydrolysis of the sap on the water bath 
with ro per cent HCl, and total hydrolyzable carbohydrates of a 
given weight of tissue after 4 hours’ hydrolysis with 5 per cent HCl. 
The last term thus covers all substances which break up with 
5 per cent HCl to give reducing sugars, consisting in this instance 
of a variety of polysaccharides, including pentosans and probably 
hemi-celluloses as well as starch, besides the soluble sugars. In a 
rough way it measures the stored nutriment of the plant. A more 
detailed description of the methods used is given in the previous 
article. 
The results of the observation of no. 23 and of its final analysis 
are shown in fig. 1 and table I, and the conclusions to be drawn 
from them may be summarized briefly as follows. As would 
naturally be expected, the curve of water loss shows a distinct 
break at the point where the plant was transferred from the rigorous 
conditions of the laboratory court to the more equable conditions 
of the dark chamber. A more interesting finding is the uniformity 
of the rate of the water loss, which, in the already well desiccated 
plant, seemed almost independent of seasonal changes. Small 
variations did indeed occur, but they cannot be well shown on the 
scale of the accompanying tracing. Inasmuch as the temperature 
variations of the surrounding air must have been large, the dark 
chamber being located in an unheated portion of the laboratory 
building, the strong influence of light upon evaporation is shown, 
for very noticeable seasonal changes in evaporation were observed 
in other plants drying at fairly equable temperatures even in the 
diffuse light of the laboratory. 
Several distinct changes have taken place in the sugar concen- 
tration. A high acidity is noted, which is explained by the con- 
ditions of the plant’s confinement. It has been repeatedly brought 
