12 ORGANIC CONSTITUENTS. 



The products of tlie oxidation of protein occur constantly in 

 tlie blood; tliey are formed in the lungs from fibrin, a sub- 

 stance which has been shown by Scherer to possess the pro- 

 perty of absorbing oxygen when in a moist state. The fibrin, 

 oxidised in the lungs is, according to Mulder, the principal, if 

 not the only, carrier of the oxygen of the air ; it is especially 

 this substance from which the secretions are formed. 



In inflammatory conditions, a considerably larger quantity 

 of protein in an oxidised state, is contained in the body, than 

 is found in a normal state. ^ 



These compounds (or at least one of them) are also found in 

 pus, the substance termed pyin being in reality tritoxide of pro- 

 tein ; in false membranes, in cooked meat, and in vitelline sub- 

 stance ; in the last-named substance we meet with a sulphuret 

 of the binoxide of protein. 



Mulder has recently obtained a third oxide of protein, repre- 

 sented by the formula C^„ H3, N^ O^^, by boiling yeast in water. 

 It occurs in a state of solution. 



' The examination of the foregoing facts leads to some very important conchisions. 

 We see, for instance, that, by the ebullition of meat, protein is converted into two 

 oxides, and is thus no more presented to the organism as a means of nutrition in the 

 form of protein, but one part is converted into binoxide, which is hard and sparingly 

 soluble, while another portion is changed into the soluble tritoxide, and occurs in 

 broth, extract of meat, &c. According to Mulder, the interior of roasted meat un- 

 dergoes a change analogous to that which is produced by ebullition. As the effects 

 of ebullition upon albumen differ from those on fibrin, in evolving only the tritoxide 

 of protein, boiled albumen must be perfectly distinct from boiled or roast meat as a 

 means of nourishment. 



The process of inflammation also appears essentially as a higher grade of oxida- 

 tion. The allmmen of the blood, which furnishes only tritoxide by ebullition, pro- 

 bably takes no part in the change : we may conclude that it is effected by the fibrin 

 alone, which, as we know, absorbs oxygen from the air, and is with so much compa- 

 rative facility converted into l)inoxide and tritoxide of protein. During the height 

 of inflammation, there is a great excess of the oxides of ])rotein in the blood; in a 

 state of health they are, doubtless, present, but in much smaller proportions. Between 

 these extremes there may be many intermediate states induced by different disor- 

 ders. Respiration may consequently be regarded as a true oxidation of the blood, 

 or rather of the protein ; and in inflammation, in Mliich the blood contains a greater 

 quantity of binoxide and tritoxide of protein than in the healthy state, this body 

 becomes more thoroughly oxidised. Hence it occurs that, in the acceleration of the 

 act of respiration, in fevers, for example, inflammation so easily supervenes after any 

 violent or sustained efforts. Every paroxysm of fever must necessarily cause the 

 formation of a greater quantity of oxidised protein in the system, and every augmen- 



