Soluble Ferments Digestion. 233 



with the substance it appears to affect. It may, in the process of diges- 

 tion, mingle with it and accompany it in its movements through parts of 

 the organized body, but still it retains its identity and, in some cases, 

 appears to return to the organ in which it originated. Since its effects 

 cannot be attributed to giving up its own materials or to receiving any, 

 they must be due in some way to its mere presence. And this, I think, 

 is the fact. 



The diastase is merely a catalytic agent inducing, by its influence, a 

 union between a molecule of starch and a molecule of water, and I sup- 

 pose it does this merely by modifying the shape of one or other of the 

 molecules without otherwise changing the amount or kind of substance 

 it contains. It is the same sort of phenomenon that occurs when sul- 

 phurous acid gas (S 2 ) and air or oxygen are mixed together and then 

 brought into contact with hot platinum sponge. Without loss or 

 change to the sponge, the sulphurous acid gas is made to take up enough 

 of the oxygen to form sulphuric acid (S 3 y Other substances, such as 

 clay, pumice-stone, and the oxides of copper, chromium, and iron, will 

 perform the same service as the platinum sponge in this case. Their 

 mere presence causes the union. 



Every particle or body of matter is subject to electrical movement or 

 electrical tension, the manner, direction or position of which depends 

 upon the polarities of the body, which in turn depend upon the relative 

 position of its molecules and atoms. The introduction of any body into 

 the environment of any other will disturb its electrical condition ; and it 

 may disturb it to the point of dissolution of the body, or it may cause 

 such new arrangement of its component atoms as to give it new polari- 

 ties and new affinities. This last is what appears to be done in the case 

 of catalysis, and in the operation of the diastase. The production of 

 the ferment in plants and in some cold-blooded animals, takes place at 

 certain seasons only, and this proves that it is regulated in some way 

 by influences outside of the organism. Evidently the rise in tempera- 

 ture which takes place in spring furnishes the force by which the diasta- 

 sic molecule is shaped in, and detached from, its mother gland. 



In the warm-blooded animals which do not hibernate, and in the 

 perpetually growing plants of the tropics, heat is always present and the 

 ferment is always in stock. 



The diastase may be regarded as a cross between a mineral compound 

 and an organism. It is not a full fledged organism because it has not 

 the power of reproduction or self perpetuation. There are many qual- 

 ities in common between it and the yeast plant which always has it in 

 companionship, and there are some contrasts. The organic ferment, by 

 its organization, appears to be able to resist certain influences to which 

 the diastase succumbs ; for example, its activity is not prohibited by 



