o4G TRANSACTIONS AND PROCEEDINGS OF THE [Sess. LX. 



following observations by Molisch seem to shed a little 

 light on the jjroblem. Molisch (12) found that in many 

 cases, e.fj. brightly coloured leaves of Coleiis, the anthocyan 

 was so rapidly destro3'ed on boiling with water, that it was 

 impossible to obtain a solution. This rapid destruction, he 

 believes, apparently with good reason, to be due to alkaline 

 substances contained in the protoplasm of the cells. While 

 the cells are living, the cell-sap with its contained anthocyan 

 is separated from the alkaline protoplasm ; in dpng cells, 

 a mingling takes place, and in some cases the alkalinity of 

 the protoplasm is sufficient to destroy the anthocyan (e.g. 

 effect of strong alkalies as detailed above). Molisch finds 

 that this destruction of anthocyan is especially liable to 

 take place in cells which contain chlorophyll. As this 

 cannot easily be a direct effect, he concludes that, in 

 chlorophyll-containing cells, the conditions for the pro- 

 duction of alkaline substance must be especially favourable. 

 Further, he found that leaves, whose anthocyan did not 

 change at death, were especially remarkable for the acidity 

 of their cell-sap. 



Xow, although Molisch does not himself make the 

 suggestion, it seems hardly possible to doubt that the 

 alkalinity of the protoplasm must have some effect upon 

 the anthocyan of the cell-sap during life ; there must 

 surely be a constant process of diffusion going on between 

 protoplasm and cell-sap. If this be so we can readily 

 understand how it is that anthocyan is so frequently 

 associated with diminishing chlorophyll. The particular 

 (alkaline) condition of the protoplasm, which is associated 

 with the development of chlorophyll, is unfavourable to 

 the production of anthocyan tending to decolourise it ; the 

 process being probably the " reconversion into tannin " of 

 Wigand. Conversely, conditions which are unfavourable 

 to the development of chlorophyll are directly favourable 

 to the de\'elopment of anthocyan. This is probably the 

 physiological reason for that association of anthocyan with 

 diminishing powers of assimilation which we have already 

 noticed as a fact of experience. 



The following table is intended to illustrate the suggested 

 relations between the various cliromogens of glucoside 

 nature found in flowering-plants : — 



