326 DR ALISON'S OBSERVATIONS ON 



seems evidently to denote that it is most probably formed from the elements of 

 albumen, by a farther separation of carbon and hydrogen, aided by the agency of 

 the oxygen of the air. Liebig seems to consider it as certain, that this separa- 

 tion mnst be from the elements of albumen, and, therefore, that gelatin can only 

 be formed from albumen ; but it is possible, also, that it may take place from 

 the elements of starch with ammonia, oil being formed at the same time. 



If we take the numbers given by Mulder as representing the composition of 

 gelatin, this appears very distinctly. Thus, 



To starch, 

 Add ammonia. 



From this subtract, 

 Elements of gelatin, 



81 ... 88 85 

 And again, 5 equivalents of fat, 60 ... 50 5 



21 - 38 80 



which is exactly 21 equivalents of carbonic acid with 58 of water, excreted by 

 the skin and lungs. 



The "tritoxide of protein," lately so fully considered by Mulder, approaches 

 so nearly in its properties to gelatin, that we may presume its formation will de- 

 pend on nearly the same conditions ; and accordingly we find, that it may be 

 formed from albumen by the long-continued application of heat, air, and water ; 

 and that it is formed in large quantities in inflamed parts, where the stagnation 

 of arterial blood (carrying oxygen) and the increased temj^erature plainly indi- 

 cate that an increased application of oxygen is going on. 



But as there is a remarkable discrepancy of statement as to the chemical rela- 

 tion of gelatin to the albuminous compounds, we must regard the precise na- 

 ture of the change effected in this department of the animal economy as some- 

 what doubtful. 



In thus attempting to trace the nature of the processes, wherever they may 

 be carried on, by which carbon, nitrogen, hydrogen, and oxygen, uniting with 

 other elements in smaller proportion, fall into the combinations which constitute 

 the animal textures, and in attempting likewise to assign the iirovince of the 

 vital affinities in these processes, we must admit very material deficiency of in- 

 fi)rmation. We do not perceive, for example, how it should happen that the amy- 

 laceous matter, which forms the greater part of the ingesta of so many animals. 



