Variations in the Carbohydrate Content. 1 1 7 



realise the degree of accuracy of the results. He realises, for 

 instance, that " this hranch 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 taUen, and he draws conclusions only from wide 

 differences in sugar contents. 



As a result of his analyses. Parkin finds that during any single 

 day ill 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 XXXI 1. 



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. 



3.30 p.m. 



Table XXXIll. 



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 temperatui-e 3-3"C. 



8 a.m. 



