28 SOME RECENT RESEARCHES IN PLANT PHYSIOLOGY 



the osmotic pressure falls, and also the mean molecular 

 weight, since the percentage of sugars in the sap solutes 

 has diminished. That the exposed control has normal 

 values is probably due to rapid assimilation during the 

 early morning. 



SUMMARY OF RESULTS OF RESEARCHES ON THE 

 SNOWDROP. 



On the whole, Parkin's work confirms that of Brown and 

 Morris in indicating sucrose as the first sugar to be formed 

 in photosynthesis. It must, however, be pointed out that 

 mere accumulation of sucrose is not in itself direct evidence, 

 as this may be equally well explained according to the views 

 put forward by Strakosch. With his work, that of Parkin 

 on the constancy of the hexoses is in good agreement. To 

 the present writer the excess of fructose over glucose, and 

 the almost entire absence of the latter sugar at times of 

 rapid photosynthesis, are more telling facts in favour of 

 the sucrose theory. The experiments of both Strakosch and 

 Parkin point to sucrose as the sugar which is chiefly con- 

 cerned in translocation downwards, whereas Brown and 

 Morris believe that before translocation the sucrose is 

 inverted. 



THE DIURNAL CARBOHYDRATE CYCLE OF THE MANGOLD. 

 The first investigation on the cycle of changes taking 

 place daily in the foliage leaf was that of Campbell (1912), 

 carried out in 1910, though not published till over a year 

 later. He analyzed the carbohydrates of the mangold 

 (Beta maritima) leaf. The methods employed for this 

 purpose were such as to give comparable results, though 

 they were not rigorously accurate. One possible source of 

 error, affecting all the results, appears to have been over- 

 looked. This occurred in the concentration of the extract 



