XUTRTTTVi; VALUES. 55 



bility, capability of undergoing osmotic absorption, and oxidizability 

 for the production of energy. At present, no definite numerical state- 

 ment of the relative nutritive values of nitrogenous bodies of these 

 three classes can be made. It seems much to be desired that more 

 extended experiments than have so far been recorded should be made 

 upon living animals (as far as possible upon human beings) to deter- 

 mine the utilization of both the gelatinoids and the simpler amids. 

 The latter no doubt undergo oxidation to some extent in the animal 

 body, and produce some energy in consequence. It is probably true 

 of these simpler amidic substances that much larger quantities than 

 analysis exhibits as constituents of the food consumed, or than analy- 

 sis detects among the residue of food rejected from the body without 

 having undergone complete oxidation, may be constantly formed 

 among the earlier products of the metabolism of the proteids, and 

 afterwards themselves undergo further change into the simpler and 

 more stable forms of carbon dioxid, water, and urea. 



In the animal body the amido acids are acted upon in two ways; 

 that is, they are converted into the corresponding fixed acids or car- 

 bonic acid is split off, leading to the formation of Brieger's diamins, 

 or it is possible for both of these processes to take place. Usually the 

 albumins are converted in the alimentary tract by the four proteo- 

 lytic ferments (pepsin, trypsin, erepsin, and arginase) into primary 

 crystalline dissociation products, namely, the amido acids, which are 

 absorbed in this form. Whether a part of the albumin taken as food 

 can or can not be absorbed in the form of albumoses, peptones, and 

 peptids remains to be determined. 



Meat preparations of the sort included in this report are largely 

 used by the sick and the young. Their use is recommended fre- 

 quently by physicians who may not have taken the trouble to ascer- 

 tain the true nutritive value of the product prescribed. It seems to be 

 the general consensus of opinion among scientific investigators who 

 have studied this question that the food value of these meat extracts 

 is rather limited, and although they are a source of energy to the 

 body they must not be looked upon as representing in any notable 

 degree the food value of the beef or other meat from which they are 

 derived. When prepared under the best possible conditions a com- 

 mercial meat extract is, of necessity, in order that it may not spoil, 

 deprived of the greater part of the coagulable proteids, which con- 

 stitute the chief nutritious elements of the juice. It is fair to state 

 that many manufacturers make no claim as to the food value of their 

 preparations, only a comparatively few making extravagant state- 

 ments as to the nutritive value of these products. 



Preparations of this character are not wholly valueless in the sick 

 room, for they possess stimulating qualities, and in the kitchen they 



