304 Extracts fronn the Journals. [Oct., 



that more or less of such is required for that purpose according as 

 it is deiicient or abounds in nitrogen as a constituent. It would 

 far exceed the limits of this paper to speak in detail of the vari- 

 ous modifications of these azotized constituents. Suffice it to say 

 that albumen, fibrin, and casein, whether of animal or vegetable 

 origin, are identical. 



Mulder has established the existence of a proximate principle 

 common to them all, as their basis: to this substance he applies 

 the name protein — the difference between the compounds being 

 simply in the presence of small and varying quantities of sulphur 

 and phosphorus. For the composition of protein, Mulder gives 

 the empirical formulae — C40 H3, N5 0,2 (that is, 40 carbon, 

 31 hydrogen, 5 nitrogen, and 12 oxygen.) If Pr. is made to re- 

 present this substance symbolically, the following formula will 

 give an approximation to, if not the true composition of the 

 proximate azotized elements of nutrition: 



Albumen (of blood) - - - 10 Pr.H-2 S+P 



Fibrin, 10Pr.+ S+P 



Casein, 10 Pr.+ S 



In the above, S and P respectively represent sulphur and phos- 

 phorus. We now pass on to the second division, the non-azot- 

 ized elements of nutrition. 



For the due discharge of its various functions, it is essential 

 that the animal body should be kept at a certain temperature un- 

 der whatever varying circumstances it may be placed; this is 

 ibund to be in man from 98 to 100 deg., and in cattle about 100 

 deg.; slight variations in the standard are found in the various 

 grades of the animal kingdom, according to the habits of the in- 

 dividual and the functions it has to dischai-ge, as well as its mode 

 of life. 



This important end is attained by respiration. Respiration in 

 a chemical point of view, is simply the union of oxygen from the 

 air with carbon contained in the blood. This process of olow 

 combustion of carbon in the lungs is continual, and thus is afford- 

 ed the due amount of heat to the animal economy. Despretz has 

 shown that 1 oz. of carbon by combustion (that is, union with 

 oxygen) evolves 14.207 deg. of heat; Boussingault takes, as a 

 mean, the daily consumption of carbon by- man to be 14 oz. 

 Now 14X14.207=198.898 deg. of heat given out by man in 24 

 hours; and by deducting from this the loss of heat by vaporiza- 

 tion of water through the skin and lungs, we have left about 

 146.380 deg. of heat for the various purposes of the animal eco- 

 nomy (Liebig). Thus, then, it is evident that the amount of heat 

 developed bears a simple proportion to the amount- of carbon 

 consumed by oxidation in the lungs, and this will be dependent 



