524 PHYSIOLOGY AT THE FARM. 



tion of urea, we find the large percentage of carbon in the 

 albuminoid proximate principles reduced to a minimum in 

 urea, there being 54 per cent of carbon in proteine, their re- 

 presentative, and only 20 per cent in urea. The hydrogen is, 

 indeed, in larger proportion than can be changed to water by 

 the oxygen, the hydrogen being 6.8 per cent to 24.3 per cent 

 of oxygen ; but if we suppose urea, or some representative of 

 urea, to be formed immediately on the decomposition of the 

 muscular tissue, then nearly the whole of the hydrogen of that 

 tissue, and but a little more oxygen, is required for urea for 

 there are in proteine 6.8 per cent of hydrogen and 24.3 per 

 cent of oxygen, and in urea 6 per cent of hydrogen and 27 per 

 cent of oxygen. But when we look to the amount of nitrogen 

 in urea as compared with its amount in proteine, we find a 

 very great difference, the percentage of nitrogen in urea being 

 47, while in proteine the percentage is no more than 14. 

 Thus, several like quantities by weight of proteine in the mus- 

 cular tissue must be decomposed for every like quantity by 

 weight of urea produced. And this is indicated by the equi- 

 valents of the two compounds that of urea being 60, while 

 that of proteine is more than six times greater, namely, 395. 

 What becomes of the hydrogen and oxygen unprovided for, 

 when several proportions of proteine are decomposed to furnish 

 the requisite amount of nitrogen for one equivalent of urea, is 

 subject for investigation. There is also a large proportion of 

 carbon in the equivalent of proteine, as compared with its 

 amount in urea, to be accounted for. This last point is more 

 easily explained than that which precedes. For the decom- 

 position, for example, of muscle under contraction is the result 

 of the energy produced when the oxygen acquired by the 

 blood in respiration attacks the proteine atoms, and seizes their 

 carbon, so as to reduce it to the less proportion in which it 

 exists in urea. It would appear, then, that if a small allow- 



