8o SACCHAROMYCES 



the Mycetozoa (p. 54), and probably it or some similar pep- 

 tonizing or proteolytic ferment effects this change in all 

 organisms which have the power of digesting proteids. 

 Another instance is diastase, which effects the conversion 

 of starch into grape sugar : it is present in germinating 

 barley (see p. 74), and an infinitesimal quantity of it can 

 convert immense quantities of starch. The ptyalin of our 

 own saliva has a like action, and probably some similar 

 diastatic or amylolytic ferment is present in the Mycetozoa 

 which, as we saw (p. 54), can digest cooked starch. 



