60 SOME RECENT RESEARCHES IN PLANT PHYSIOLOGY 



leaves of the following both by day and by night : Sphagnum 

 cymbifolium, Brachythecium rivulare, Dicranum majus, and 

 Thuidium tamariscinum. Quite in keeping with the 

 evidence as to the absence of starch from the leaves of 

 S. cymbifolium is the complete absence of diastase also, 

 but this enzyme is present in those of Polytrichum commune 

 which contain starch. 



As an illustration of the quantities in which the sugars 

 are found in P. commune, Mason's analyses are quoted. 

 Reductions were carried out with Benedict's solution, and 

 the inversion of maltose was effected by boiling with hydro- 

 chloric acid according to the procedure of Brown and 

 Morris. This, though convenient, is admittedly faulty. 

 The stems and leaves in their normal proportions were 

 taken for analysis, results being given as percentages of 



the moist weight. 



TABLE XX. 



From the above it may be seen that much sucrose has 

 been used up during storage in the dark, and also a little 

 hexose has disappeared in spite of the replenishing of 

 glucose and fructose by inversion of sucrose, and of glu- 

 cose by that of maltose. The last-named sugar shows a 

 small increase owing to the mobilization of starch reserves. 



The ratios which the various sugars bear to each other 

 in the leaves and stems of P. commune are given in the 

 following table. The actual percentages could not be 

 determined owing to the time required for separating the 



