li'tl Prof. J. R. Green. On the Hfrmimition of the, [Feb. 



of excretion of the enzyme, which can readily be detected in tl 

 culture Said. 



The reserve stores of the pollen grain differ in various specie 

 They include starch, possibly in some cases dextrin, cane si 

 maltose, and glucose. The intracellular action of diastase can 

 noticed in the cases in which it is present, by the transformation 

 the starch granules as they pass along the tube, iodine stainii 

 them blue in the grain and upper part of the tube, then purple, ai 

 finally almost red as the tip is approached; indicating thus 

 gradually increasing formation of dextrin, one of the accompaniment 

 of starch digestion. Quantitative estimations of the sugars 

 quoted in detail in the paper. 



The distribution of starch in the style of the Lily was found to ha^ 

 a close relation to the progress of the pollen tube. The cells linii 

 the cavity of the style, and the cells of the loose conducting tissi 

 abutting on it, were found to contain starch grains, in greater or lc 

 amounts, varying with the species and with the age of the individi 

 style. The outer soft tissue of the fibro-vascular bundles of thi 

 organ were also charged with crowds of starch grains, indicating 

 transport of tbis reserve material from the leaves. Cane snj 

 maltose, and possibly glucose, were found to be the sugars prese 

 in the various styles examined. 



In longitudinal preparations the starch was found to stop si 

 some few mm. below the stigma, suggesting the view that tl 

 reserves in the style are intended to supplement those in the polle 

 grain, the latter being utilised in the early stages of germination. 



Not only reserve materials can be found in the style, but in cei 

 cases diastase also exists. 



The action of the enzymes of the pollen is thus found to be partly 

 intracellular, digesting the contents of the pollen grain, and 

 extracellular, being excreted into the tissue of the style to we 

 upon the external reserves. This is particularly noteworthy in tl 

 case of Narcissus, where the grain contains invertase, but, accordii 

 to Van Tieghem, no cane sugar. The latter is found in consideral 

 quantity in the style. 



The development of the enzyme is not a phenomenon of starvatu 

 The increased production noted is partly an effect of the absorpt 

 of food material which appears to act as a stimulant to its pi 

 duction. 



Evidence on this point is quoted in the paper. 



The absorption of food material often leads to an increase of st 

 in the grain and in the tube. 



The increase of enzyme noted in certain cases lends a cert 

 amount of support to the view that the enzyme exists in the polle 

 grain in the form of a zymogen. Some evidence bearing out tl 



