ACTION OF MEDICINAL AGENTS. 165 



the growth or reproduction of organs, combines with the 

 substance of the living parts, and produces, by its union 

 with their elements, the act of transformation which we 

 have called the change of matter. 



78. It is obvious, that all compounds, of whatever 

 kind, which are present in the capillaries, whether sepa- 

 rated there, or introduced by endosmosis (A) or imbibi- 

 tion, if not altogether incapable of uniting with oxygen, 

 must, when in contact with the arterialized globules, the 

 carriers of oxygen, be affected exactly in the same way 

 as the solids forming part of living organs. These com- 

 pounds, or their elements, will enter into combination 

 with oxygen, and in this case there will either be no 

 change of matter, or that change will exhibit itself in 

 another form, yielding products of a different kind. 



79. The conception, then, of a change in the two 

 qualities of the blood above alluded to, by means of a 

 foreign body contained in the blood or introduced into 

 the circulation (a medicinal agent), presupposes two 

 kinds of operation. 



Assuming, that the remedy cannot enter into any such 

 chemical union with the constituents of the blood as puts 

 an end to the vital activity ; assuming, further, that it is 

 not in a condition of transformation capable of being 

 communicated to the constituents of the blood or of the 

 organs, and of continuing in them ; assuming, lastly, 

 that it is incapable, by its contact with the living parts, 

 of putting a stop to the change of matter, the trans- 

 formation of their elements ; then, in order to discover 

 the modus operandi of this class of medicinal agents, 



