THE ACTIONS OF FORCES ON ORGANIC MATTER. 43 



utilize this same principle of initiating extensive changes 

 among comparatively stable compounds, by the help of com- 

 pounds much less stable, but we employ for the purpose 

 compounds of the same general class. Our modern method 

 of firing a gun is to place in close proximity with the gun- 

 powder which we wish to decompose or explode, a small por- 

 tion of fulminating powder, which is decomposed or exploded 

 with extreme facility, and which, on decomposing, communi- 

 cates the consequent molecular disturbance to the less-easily 

 decomposed gunpowder. When we ask what this fulminating 

 powder is composed of, we find that it is a nitrogenous salt.* 



Thus, besides the molecular re-arrangements produced in 

 organic matter by direct chemical action, there are others of 

 kindred importance produced by indirect chemical action. 

 Indeed, the inference that some of the leading transforma- 

 tions occurring in the animal organism, are due to this 

 so-called catalysis, appears necessitated by the general aspect 

 of the facts, apart from any such detailed interpretations as 

 the foregoing. We know that various amylaceous and 

 saccharine matters taken as food do not appear in the 

 excreta, and must therefore be decomposed in their course 

 through the body. We know that these matters do not 

 become components of the tissues, but only of the con- 

 tained liquids and solids ; and that thus their metamorphosis 

 is not a direct result of tissue-change. We know that their 

 stability is such that the thermal and chemical forces to 

 which they are exposed in the body, cannot alone decom- 

 pose them. The only explanation open to us, therefore, is 

 that the transformation of these carbo-hydrates into carbonic 

 acid and water, is due to communicated chemical action. 



* After this long interval during which other subjects have occupied me, 

 I now find that the current view is similar to the view above set forth, in so 

 far that a small molecular disturbance is supposed suddenly to initiate a great 

 one, producing a change compared to an explosion. But while, of two pro- 

 posed interpretations, one is that the fuse is nitrogenous and the charge a 

 carbo-hydrate, the other is that both are nitrogenous. The relative probabili- 

 ties of these alternative views will be considered in a subsequent chapter. 



