CHEMISTRY. 367 



of last year, have been completed. These experiments show that this 

 enzj^me exerts its optimum saccharogenic activity at the definite 

 hydrogen ion concentration (determined by the electrometric method 

 and expressed in Sorensen's notation) of Ph = 4.4 ± 0.2, irrespective 

 of whether this reaction is obtained b}^ the addition of a strong acid 

 (hydrochloric, nitric, sulphuric), a weak acid (acetic, propionic, phos- 

 phoric), or a weakly acid salt (primary sodium or potassium phosphate). 

 These results were published in full in the Journal of the American 

 Chemical Society for March 1915. An analogous study of the optimum 

 hydrogen ion concentration for pancreatic amylase is now in progress. 



Purification experiments upon the amylase of Asperg'^'Uns oryzce 

 have resulted in products of about twentj^-five times the activity of 

 the commercial preparations from this fungus. The laboratory puri- 

 fication results in a rise of nitrogen content along with diastatic activity, 

 but the best preparations yet obtained are less highly nitrogenous and 

 have less saccharogenic power than the purified preparations of either 

 pancreatic or malt amylase. While further work upon the purification 

 of this amylase is contemplated, the experiments already completed 

 have provided material for certain comparisons with the pancreatic 

 and malt amylases. 



The question whether maltose or glucose should be considered the 

 true end-product of the action of amylase upon starch has been studied, 

 using the three amylases above mentioned both in the natural or 

 commercial and in the purified forms. In all of these cases, under 

 conditions such as obtain in the determination of diastatic power, 

 maltose is found to be the chief reducing sugar formed. In general 

 it so far predominates as to justify the custom of calculating the reduc- 

 ing power of the products of amjdase action as due to maltose. The 

 formation of a small amount of glucose, even by the purified amylases, 

 is, however, demonstrable in experiments which are sufficiently pro- 

 longed, and the relative amount of glucose formed is plainly greater 

 in the case of the fungus amjdase. 



Our unexpected discovery of three years ago, that purified pan- 

 creatic amylase is also an active protease, has been briefly noted in 

 previous pubhcations. Having made during the past year a com- 

 parative examination of several methods for the study of proteolytic 

 action, a more detailed investigation of the proteolytic activity of our 

 purified amylase preparations is now being undertaken. 



The activation of the amylases by neutral salts and the development 

 of a better method for the determination of amyloclastic power are also 

 under investigation, and we hope to take up in the near future a 

 detailed quantitative study of the course of the reaction of starch 

 hydrolysis under the influence of purified amylases of different origin. 



The efficient aid of the collaborators in this investigation, whether 

 as research assistants or volunteers, is gratefully acknowledged. 



