50 SILOS, ENSILAGE AKD SILAGE. 



These "soluble ferments are all derived directly from 

 living organisms, in the midst of which they originate/'* 

 but they must not be confounded with the true, or organ- 

 ized ferments which act in a different manner. 



These zymases appear to be important factors in the 

 processes of assimilation and nutrition in all forms of 

 vegetable and animal life. 



The starch formed in the green cells of the leaf in 

 daylight is transformed into glucose (grape sugar) at 

 night, and transferred to the body of the plant, where 

 it is stored in the form of starch or cane sugar, as reserve 

 materials for the future use of the plant. In the tuber- 

 ous roots of beets, and in the stalks of the sugar cane 

 and sorghum, for example, cane sugar is stored in con- 

 siderable quantities, as reserve material, and starch, in 

 the same way, is stored in the tubers of the potato. 

 When needed again they are reconverted into glucose, 

 by a zymase, elaborated by the living cells of the plant, 

 and transported again where they can serve a useful pur- 

 pose in its economy. 



The salivary and pancreatic glands of the higher ani- 

 mals secrete zymases which convert starch and cane 

 sugar into glucose, that is stored up by the liver in the 

 form of glycogen, which appears to be reconverted into 

 glucose, and distributed through the general circulation 

 as the exigences of the system require. The gastric and 

 pancreatic secretions likewise contain soluble ferments 

 that convert insoluble proteids into soluble and diffusible 

 peptones, and even in plants peptonizing ferments are 

 secreted by the cells to serve a similar purpose. It like- 

 wise appears that the elaboration of soluble ferments in 

 animals is not confined to the special glandular organs of 

 secretion, but the general tissues of the system, as in 

 plants, are to a greater or less extent concerned in per- 

 forming the same function. It may, in fact, be said 



* Schutzenberger on Fermentation, p. 273. 



