576 



VITAL ACTIONS OF THE LOWER FUNGI. 



Diastatic 

 ferments. 



of the exciting agents of fermentation. For these 

 reasons the chemical ferments require to be considered 

 more in detail in this place. 



We distinguish the following kinds of chemical fer- 

 ments : 



1. Diastatic ferments. These convert starch into 

 forms of glucose (maltose, dextrose, &c.), and, as a rule, 

 they only act where the reaction is neutral or slightly 

 acid, but not where it is alkaline. They occur fre- 

 quently in animals and plants. Of animal ferments we 

 have, belonging to this group, the ptyalin of the saliva ; 

 the ferment of the pancreatic juice, which, when the 

 reaction is alkaline, converts starch into glucose ; the 

 ferment contained in the liver, which acts on glyocogen ; 

 two ferments present in the urine (Selmi,* Bechamp 

 and Baltusf), &c. We find the diastatic ferments very 

 widely distributed in plants ; they occur in specially 

 large quantities in germinating wheat, in malt, and also 

 in the most various organs of plants, in young seeds, 

 leaves, &c. (BrasseJ). 



Diastatic ferment has been frequently demonstrated 

 change of the during the last few years as a product of the tissue 

 change of bacteria. Marcano found a ferment of this 

 kind in bacteria which frequently occur in the external 

 sheath of maize ; Hueppe || demonstrated a diastatic 

 action in connection with the bacterium lactis ; Miller ^f 

 isolated a species of bacteria from human intestinal 

 contents which was able to dissolve starch. Wortmann** 

 was also able to demonstrate energetic diastatic action 

 in a mixture of bacteria which he obtained from decom- 

 posing beans or potatoes, and which he cultivated in a 

 mixture of nutrient salts and wheat starch. That the 

 solution of the starch in these cases really depends on 

 the production of a ferment can, however, only be re- 



* Selmi, Atti del Lincei, vol. v. 



t Bechamp und Baltus, Compt. rend., vol. 92. 



X Brasse, Ibid., vol. 99. 



Marcano, Ibid., vol. 95. 



|| Hueppe, Mitth. a. d. Kais. Ges. A., vol. ii. 



f Miller, Devtsch. med. Woch., 1885, Nr. 49. 



** Wortmann, Z.f.physioL Chem., vol. vi. 



As products 

 of the tissue 



