308 A CHEMICO-PHYSIOLOGICAL STUDY OF 



not be detected by the biuret reaction. Whether this fact is 

 to be taken as an indication of their excretion by the urine 

 in the form of amide-acids, etc., formed through proteolytic 

 action in the kidneys, or whether it is due to decomposition 

 taking place elsewhere, or to a storing up within the body we 

 cannot say. 



OBSERVATIONS ON THE CHEMICAL NATURE AND GENERAL 

 PROPERTIES OP THE PROTEID CLEAVAGE PRODUCTS 

 USED IN THE PRECEDING EXPERIMENTS. 



AMONG the many earlier results obtained in the attempt to 

 throw light upon the chemical nature of the proteid molecule 

 those recorded by Schutzenberger * were particularly sugges- 

 tive, especially from a physiological standpoint. The break- 

 ing down of the proteid molecule into two equal parts by the 

 action of 3 to 5 per cent sulphuric acid at 100 C. naturally 

 suggested the possible existence of two distinct groups in the 

 mother proteid, a suggestion which was intensified by the 

 observations of Kiihne f that these two cleavage or alteration 

 products behaved quite differently toward alkaline pancreatic 

 juice. Schutzenberger through his hydrolysis of coagulated 

 egg-albumin by dilute sulphuric acid obtained an insoluble 

 residue equal to about 50 per cent of the original proteid, to 

 which he gave the name of hemiprotein, while the 50 per cent 

 of soluble matter was represented by a row of substances 

 among which leucin, tyrosin, peptone, and albumoses (as now 

 termed) were conspicuous. As Schutzenberger pointed out, it 

 was quite evident that these latter products resulting from 

 this hydrolysis represented a half of the proteid molecule much 

 less stable than that portion of the proteid from which the so- 

 called hemiprotein was derived. This more readily decompos- 

 able half of the proteid he considered as represented by a body 



* Schutzenberger, Bulletin de la Socie'te' chimique de Paris, 1876, xxiii, and 

 xxiv. 



t Kiihne, Verhandl. d. Naturhist.-Med. Vereins zu Heidelberg, 1877, i, p. 

 236; Kiihne and Chittenden, Zeitschr. f. Biologic, 1883, xix, p. 159. 



