94 VETEEINAEY HYGIENE 



Under the designation Albuminoids is grouped proteid 

 substances closely allied to albumen, yet differing from it 

 in some important particulars, and to this class belongs 

 gelatin, 7nucin, keratin, etc. 



Most of these animal proteids and albuminoids have, 

 their counterpart in the vegetable kingdom. The plant 

 can obtain its nitrogen from ammonia and nitrates, and 

 elaborate this into the complex proteid. The animal 

 obtains its supply of nitrogen through the complex proteid 

 molecule, but is unable to utilize nitrogen obtained from 

 such simple substances as ammonia and nitrates. 



In animal proteid matter albumens predominate, whereas 

 in vegetable proteid globulins exist in larger amount than 

 albumens; in oats, maize, and peas, nearly the whole of 

 the proteid exists as globulin. 



When proteids and albuminoids are submitted to 

 analysis they are found to contain 



Carbon 



Hydrogen 



Oxygen 



Nitrogen 



Siilpliur 



Per Cent. 



52-54 



7 

 21-24 

 15-17 

 1- 1-5 



There is a remarkable similarity in composition of all 

 albumens. Some contain more carbon than others, and 

 some are richer or poorer in nitrogen than others, but 

 these differences which enable the chemist to group them, 

 do not suffice to lead to their identification. On the whole 

 it may be said that vegetable albumen contains more 

 nitrogen and less carbon than animal albumen. 



A diet which contains no nitrogen, no matter how rich it 

 may be in other principles, is a starvation diet. There is 

 nothing which can replace proteid in a food, even the 

 albuminoids, gelatin, chondrin, and keratin, have not the 

 same nutritive value as albumen itself, and cannot re- 

 place it. 



With one or two exceptions no animal can live on a 

 purely meat diet ; at some point or other the vegetable 



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