20 3Ianual of Veterinary 3Ilcrohiology. 



animals and vegetables, independent of the chloro- 

 phyllic function of the latter, require to undergo cer- 

 tain modiiications preparatory to assimilation. These 

 modifications, representing the digestion of microbes, 

 consist of a hydration accompanied or not by a split- 

 ting up of molecules. 



This phenomenon is accomplished by means of sol- 

 uble ferments secreted by the germs, and it is remark- 

 able that these digestive ferments are the same as 

 those which are found in higher beings ; thus, in the 

 case of microbes as for these last, starch is transformed 

 into dextrin by a diastase^ called amylase correspond- 

 ing to vegetable diastase, ptyalin, and to the amyla- 

 ceous ferment of the pancreatic juice. Cane sugar is 

 split up into glucose and levulose by a diastase or 

 sucrase identical with the invertin of the beet-root 

 and with the inverting ferment of the intestinal juice ; 

 albuminoid substances are peptonized by microbes 

 through the secretion by the latter of a special pepsin 

 or casease ; in the case of the casein of milk the ac- 

 tion of this last substance is preceded by that of a dias- 

 tase analogous to rennet which, like the latter, deter- 

 mines the coao-ulation of the milk. 



When we consider the great number of germs con- 

 tained within the digestive canal, the comparison 

 which we have just made between digestion in mi- 

 crobes and in the higher beings, indicates the possi- 

 bility of an adjuvant action of the former in the di- 

 gestion of animals. 



•(i)The name diastase, formerly limited to the amylaceous fer- 

 ment of vegetables, is now synonymous with soluble ferment, 

 thus amylase, sucrase, pepsin, rennet (presure), are diastases or 

 xymases. 



