328 TEANSACTIONS AND PKOCEEDINGS OF THE [Sess. LXiv, 



marked at the close of germination as at its commence- 

 ment ; while, on the other hand, the carbohydrate stores 

 are entirely used up and disappear, pointing very clearly to 

 the presence of diastase in the germinating bud. 



Fully germinated plantlets dried at 40° C, powdered 

 and macerated with a 1 per cent, solution of soluble 

 starch at 45° C. for several hours, invariably gave a slight 

 reduction with Fehling's solution, showing that a small 

 but recognisable amount of diastase was then present 

 in the plant ; while, on the other hand, no evidence 

 could be obtained of the existence of tfiis ferment in the 

 resting buds. 



As Professor Green (5) has shown that the production 

 of zymase (diastase) from the zymogen of saliva is 

 facilitated by the action of the less refrangible rays of 

 the spectrum, it seemed possible that at least a partial 

 explanation of the influence of light in the present case 

 might be found in a similar production of diastase from 

 a zymogen pre-existing in the buds ; when, however, these 

 were killed by drying at 40° C. powdered, mixed with 

 distilled water, to which a little thymol had been added 

 as a preservative, and exposed to bright sunlight for 

 periods varying from one to three weeks at the ordinary 

 temperature, no reduction was obtainable with Fehling's 

 solution, even after prolonged incubation of the mixture 

 with an equal volume of 2 per cent, starch solution, 

 showing that no diastase is formed during the experiment. 



It would seem, therefore, that the diastasogen itself is 

 not yet formed in the resting state, but probably owes 

 its origin to an action of the light antecedent to that 

 by which the diastase is formed from it. 



All the evidence thus points to the influence of light as 

 in some way facilitating the nutrient processes essential 

 to germination, and if, as seems probable, we are justified 

 in regarding the increased respiration as the outward 

 expression of an increased liberation of carbon atoms 

 from the proteid molecule, and therefore of increased 

 assimilation of carbohydrate from the stored up starch, 

 we may conclude that the primary effect of incident 

 illumination is not, at least in this case, the mere chemical 

 production of a zymase from an already formed zymogen. 



