chap, vii Enzymes and their Action 405 



first indication of the existence of a definite enzyme 

 was afforded by De Bary's work on Peziza in 1886, and 

 a more detailed account of its formation and mode of 

 action was given two years later by Marshall Ward, who 

 found it to be the active agent in the destruction of certain 

 species of Lilium by a species of Botrytis. Ward was able 

 to watch the solution of the cell membranes by a secretion 

 poured out by the growing hyphae of the fungus. Kean, 

 in 1890, and Griiss, in 1896, both found the enzyme in 

 various fungi. It was first observed among the higher 

 plants by Brown and Morris in 1890, when they were 

 investigating the changes in the barley grain during germina- 

 tion. They noticed the breaking up of the cells in contact 

 with the scutellum of the embryo and saw that this process 

 preceded the digestion of the starch. In subsequent inves- 

 tigations Brown and Escombe ascertained that a greater 

 quantity of the enzyme is furnished by the aleurone layer, 

 and they isolated it from both regions. Action upon the 

 thickened cell walls of the endosperm of Tamils was in- 

 vestigated by Gardiner in 1897, whose results confirmed 

 those of Brown and his collaborators. 



It was suggested by Sachs in 1862 that the utilization 

 of the harder and more resistent endosperms of palms 

 might be due to enzyme action, but he did not succeed 

 in detecting it. Nor did much greater success attend the 

 experiments of the present writer in 1887 ; he determined, 

 however, that the gradual consumption of the thickened 

 wails by the developing absorbing organ of the embryo is 

 attended by the formation of a reducing sugar, and he 

 found that the structure of the epithelium of the absorbing 

 organ is extremely similar in appearance to that of the 

 scutellum of the barley embryo as described by Brown and 

 Morris. The digestive changes were watched in the seeds 

 of Phoenix and Livistonia. In 1899, however, the enzyme 

 was extracted from the germinating seeds of Phoenix by 



