Carbon Assimilation. 
219 
realise the degree of accuracy of the results. He realises, for 
instance, that “ this branch of physiological chemistry is as yet in 
the tentative stage.” He prefers to make a large number of 
analyses with a moderate degree of accuracy to a few with many 
precautions taken, and he draws conclusions only from wide 
differences in sugar contents. 
As a result of his analyses, Parkin finds that during any single 
day in spring the percentage of hexose sugars in the leaf remains 
fairly constant, whereas the sucrose fluctuates greatly, increasing 
during the day and diminishing at night. Tables XXXII and 
XXXIII exhibit some of the actual numbers obtained. The values 
are given in percentages of the dry weight. 
Table XXXI1. 
Comparison of Sugars in Snowdrop Leaves picked in the early 
Morning and in the late Afternoon. 
March 7th, 1906, Cambridge. 
Maximum shade temperature 19-4°C. 
Minimum temperature, previous night 6-l°C. 
9 a.m. 
3.30 p.m. 
Sucrose 
... 
... 
11-22 
14.65 
Hexose 
... 
... 
6-35 
5-48 
Total Sugars 
... 
17-57 
20-13 
Table XXXIII. 
Comparison of Sugars in Snowdrop Leaves in the Evening 
and the following Morning. 
March 30th and 31st, 1905, Carlisle. 
Maximum shade temperature 9-7°C. 
Minimum temperature 3-3°C. 
5 30 p.m. 
8 a.m. 
Sucrose 
... 
... 
15-46 
10-84 
Hexose 
... 
... 
11-41 
12-64 
Total Sugar ... 
... 
... 
26-87 
23-48 
