ORGANIC OR COAGULABLE PRINCIPLES. 81 



constantly overcome 'and renewed in the act of assimilation and 

 dis- assimilation. It is from the more intense union of the latter 

 with organic matters that decomposition after death is prevented 

 by some of them, since thus these matters are hardened and con- 

 tracted. Thus, also, these salts become the poisons called metallic, 

 as those of arsenic, mercury, &c. 



Some of these principles (albumen, caseine, and fibrine) are in a 

 fluid state in the human body ; the rest are in a demi-solid or a 

 solid state. All these may be reduced to a more solid state by eva- 

 poration of the water which forms a part of their chemical consti- 

 tution, and which may be again recombined if they are plunged 

 into this fluid. Meantime, however, the tissues containing these 

 substances cease to perform their functions ; and if too long dried, 

 or too completely so, the readdition of water does not restore the 

 lost power. Thus these are not solid substances in a state of solu- 

 tion, but the water is a part of their chemical constitution. 



Coagulation is also merely the passage of a liquid or semi-liquid 

 substance into a solid state, and not the return of a substance in 

 solution to its primitive solid state; and the organic substances 

 alone coagulate. When coagulated, they still retain their water of 

 constitution, still united, molecule to molecule, in the organic matter, 

 as before. 



The materials for the formation of these principles arrive in the 

 organism already formed in the food (e. g. albumen, fibrine, &c.), 

 whether obtained from other animals or from vegetables; and which, 

 undergoing digestion, affords the elements for their formation in the 

 human body. But the formation occurs in the organism itself. It 

 has been suggested that those principles existing in the blood, espe- 

 cially albumen and fibrine, may have been formed from the same 

 in the food, from the occurrence of merely isomeric changes in the 

 latter. This is, however, improbable, so far as the fibrine is con- 

 cerned, as will appear in a subsequent part of this work. 



Though these principles constitute a great part of the mass of 

 the human body, the weight of other principles is, in certain organs, 

 greater than of these; e.g. the phosphate of lime in bones and teeth, 

 as compared with the osteine. 



Of the organic principles, osteine and elasticine are not found 

 early in embryonic life ; and caseine, being an element of milk, is 

 found only in the female, and after puberty. 



It is probable that neither of these principles can be directly 

 6 



