vii FERMENTS 81 



the Mycetozoa (p. 52), 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 furnished by diastase, which effects the 

 conversion of starch into grape sugar : it is present in ger- 

 minating barley (see p. 73), 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. 52), are able to digest 

 cooked starch. 



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UNIVERSITY 



