142 



COMPOSITION OF PEPTONES. 



[BOOK ii. 



that peptones do not, on ultimate organic analysis, differ in composi- 

 tion from the proteids which have yielded them, any differences 

 which exist in chemical composition falling within the limits of 

 experimental error. 



The following table exhibits the results of ultimate organic 

 analyses of fibrin and fibrin peptone, and of egg-albumin and 

 egg-albumin peptone. 



The observations of Maly and of Herth seem also to shew that 

 the peptone produced during the digestion of fibrin or of albumin is, 

 in so far as ultimate analysis can determine the matter, one body ; 

 analyses of successively precipitated fractions giving identical results. 



It must, however, be borne in mind that, in the case of bodies of 

 so large molecular weight as the proteids and the peptones, identity 

 in the results of their analysis is not sufficient to prove absolute 

 identity in composition. 



Divergent Kiihne and Chittenden have made a large number 



results obtain- of analyses of various samples of ampho-peptone, as 

 ed by Kiihne we ll as of antipeptone, but the results were marked by 

 andChittenden. a remar kabl e and suspicious departure from uniformity. 

 So great are the discrepancies that it is impossible to conceive that 

 the substances designated by the same name were the same. 



It appears to the author that in their attempts to purify and 

 completely dry the peptones, these eminent investigators, adopted 

 methods which, in all probability, profoundly modified the unstable 

 substances subjected to them. The decomposition of the barium and 

 phospho-tungstic acid compounds with sulphuric acid, and the heroic 

 methods employed to dry the bodies submitted to analysis, could 

 scarcely be expected ultimately to furnish products of which the 

 analyses would be concordant among themselves, or which would 

 exhibit any definite relationship with the mother substances from 

 which they had been prepared. 



Subjoined are the means of a large number of analyses of three 

 samples of ampho-peptone, A, B, b, as well as the means of many 

 analyses of antipeptones. 



