CHEMISTRY. 289 



appears to be of protein character, the small amounts of substance thus 

 far obtained have been utilized chiefly for study of the forms of nitro- 

 gen present. 



The eight forms of nitrogen distinguishable by the methods recently 

 developed by Van Slyke — namely, the nitrogen in the forms of 

 arginine, of histidine, of lysine, of cystine, the amino and non-amino 

 nitrogen of the hydrolytic products not precipitable by phospho- 

 tungstic acid, the melanin nitrogen, and the nitrogen liberated as 

 ammonia on direct acid hydrolysis — have been determined in the 

 preparations of highest activity thus far obtained from malt, in prepa- 

 rations of lower activity, and in the protein material more readily 

 precipitable by alcohol which had little diastatic power. The same 

 determinations have been made upon amylase preparations of maxi- 

 mum activity and of lower activity from the pancreas. Each of 

 these five products shows all the eight forms of nitrogen in propor- 

 tions well within the range exhibited by tj^pical protein substances. 

 These results make much more definite our conception of the chemical 

 nature of these enzyme preparations and may be expected to throw 

 important light upon the origin of enzymes and their chemical rela- 

 tions to antecedent substances. 



In connection with this work upon the purification of the amylases 

 and the study of their chemical nature, numerous observations upon 

 the changes in activity which the enzymes undergo in different sol- 

 vents and determinations of the quantitative relations of the amylo- 

 clastic and saccharogenic activities have been obtained, and a basis 

 for the reinterpretation of such data has been secured which may 

 greatly facilitate the clearing up of certain apparently anomalous 

 results obtained in earher investigations. 



A considerable amount of work has also been accomplished upon 

 the influence of different electrolytes and the more precise determi- 

 nation of the optimum conditions for the diastatic action of the 

 amylases. This work is being continued and arrangements are being 

 made to supplement these determinations by further direct observa- 

 tions of the behavior of the enzymes under the ultramicroscope. 



Three papers dealing respectively with the experiments upon the 

 purification of malt amylase, the comparison of amyloclastic and 

 saccharogenic powers, and the forms of nitrogen in amylase prepara- 

 tions from the pancreas and from malt have been prepared for 

 publication. 



The writer takes pleasure in acknowledging his indebtedness to 

 several collaborators. Miss M. D. Schlesinger has continued to give 

 her entire time to these investigations and at different times during 

 the year Professor H. T. Beans, Dr. A. 0. Gettler, Mr. P. W. Punnett, 

 Dr. A. R. Rose, and Mr. A. W. Thomas have cooperated in certain 

 parts of the work. 



