14 Scientific Proceedings, Royal Dublin Society. 



the possibility that levulose may be antecedent to the sucrose. They proved 

 that levulose was a down-grade product from sucrose, but failed to show 

 that it was not also an up-grade sugar. 



Parkin (7), in his work on the carbohydrates of the foliage leaf of the 

 Snow-drop, came to very similar conclusions, and further showed that: — 



1. Only three carbohydrates are present in the Snow-drop leaf, viz., 



sucrose, glucose, and fructose. 



2. The ratio of sucrose to hexoses in the leaf diminished from above 



downwards, so that the hexoses appear to be the sugars chiefly 

 concerned in translocation. 



3. During any single day of the spring the percentage of hexose sugars 



in the leaf remained fairly constant ; that of the sucrose, however, 

 increased during the day, and diminished during the night. 



A. V. Campbell (3), who traced the diurnal fluctuations in each sugar of 

 the mangold leaf, came to the following conclusions : — 



1. Reducing sugars are the first carbohydrates to be found as soon as 



daylight begins. 



2. When the reducing sugars have reached a certain concentration, the 



excess appears as sucrose. 



3. Similarly starch begins to be formed as soon as the sucrose reaches its 

 maximum. 



Strakosch (10), who experimented on the leaves of Beta vulgaris, bases 

 his conclusions chiefly on results obtained by microchemical work. 



1. Dextrose is the first sugar to appear in the process of assimilation ; in 



the small veins part of it is transformed into levulose. 



2. In the larger veins the two hexoses combine to form sucrose. 



3. Sucrose is the form in which the carbohydrates are translocated to 

 the root. 



Ruhland (9), who also worked on Beta, stated that the sugars wandered 

 from the leaf chiefly as invert-sugar, especially as levulose, to the root, where 

 they combined to form sucrose. 



Thus, Brown and Morris, Parkin and Euhland express the opinion that 

 the sugars are translocated from the leaves as hexoses, while Strakosch, and 

 apparently Campbell, hold that sucrose is the chief form in which the 

 carbohydrates leave the leaves of angiosperms. 



What follows is a summary of my preliminary experimental work with 

 the Musci. 



