OF ORGANIC TISSUES. 121 



by Pr, then nitrogen, hydrogen, and oxygen have been 

 added to it in the form of known compounds, and in 

 the following proportions, in forming the gelatinous tis- 

 sues, hair, horn, arterial membrane, &c. 



Proteine. Ammonia. Water. Oxygen. 

 Fibrine, Albumen .... Pr 

 Arterial membrane ... Pr . . . . -f- 2HO 



Chondrine Pr . . . . + 4HO + 2O - 



Hair, horn Pr -}- NH 3 ... -f 3O. 



Gelatinous tissues . . . 2Pr 4. 3NH 3 -f- HO -f 7O.* 



16. From this general statement it appears, that all 

 the tissues of the body contain, for the same amount 

 of carbon, more oxygen than the constituents of blood. 

 During their formation, oxygen, either from the atmo- 

 sphere or from the elements of water, has been added 

 to the elements of proteine. In hair and gelatinous mem- 

 brane we observe, further, an excess of nitrogen and hy- 

 drogen, and that in the proportions to form ammonia. 



Chemists are not yet agreed on the question, in what 

 manner the elements of sulphate of potash are arranged ; 

 it would therefore be going too far, were they to pro- 

 nounce arterial membrane a hydrate of proteine, chon- 

 drine a hydrated oxide of proteine, and hair and mem- 

 branes compounds of ammonia with oxides of proteine. 



The above formulae express with precision the differ- 

 ences of composition in the chief constituents of the 

 animal body ; they show, that for the same amount of 

 carbon the proportion of the other elements varies, and 

 how much more oxygen or nitrogen one compound con- 

 tains than another. 



* See Note XXVII. 

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