CHAP, vii Enzymes and their Action 403 



in the fact that the seed shows us thus a process of prepara- 

 tion of an enzyme secreted and transported from the place 

 of its secretion to act on material at some distance there- 

 from, much as is the case in the animal organism. Brown 

 and Morris studied with very considerable success the details 

 of its formation, and showed it to be a definite secretion 

 by the protoplasm. Brown and Morris further made a com- 

 parative study of the action of diastase from various sources 

 on the actual starch grains, and proved that two forms of 

 the enzyme exist in plants, which differ in the details of 

 the decomposition they set up. 



In 1895 some observations made by A. Meyer in the 

 course of the work on starch, to which we have already 

 alluded, led him to the conclusion that in the leaf a certain 

 localization of the enzyme in the cell can be determined. 

 He associated it with the chloroplast rather than the general 

 protoplasm of the cell. In the non-green parts of the plant 

 he held it to be secreted by the leucoplasts, and described 

 many cases in which the starch grains were attacked most 

 energetically where the sheath formed by the stroma of 

 the plastid was thickest. Salter, in the next year, repeated 

 and extended Meyer's observations, and noticed that the 

 starch grains became decomposed so strongly in the region 

 of contact with the plastid as to suggest that the latter 

 practically eats its way into the substance of the grain. 

 Griiss (1894), Hansteen (1894), and Puriewitsch (1896) con- 

 firmed Brown and Morris as to the process of secretion. 



The progress of the action of diastase upon starch was 

 first investigated by Payen and Persoz, who found that 

 among the products sugar and certain dextrins could be 

 detected. In 1860 Musculus recognized that dextrin and 

 sugar are produced simultaneously. About the years 1871-2 

 Griessmeyer, O'Sullivan, and Briicke, working indepen- 

 dently, showed that at least two dextrins are formed, and 

 that the sugar is maltose. It was not, however, until 1878 



c c 2 



