THE ACTIONS OF FORCES ON ORGANIC MATTER. 39 



nevertheless continues to be the part in which the independent 

 activity is most marked. 



Looking at the evidence thus brought together, do we 

 not get an insight into the part played by nitrogenous 

 matter in organic changes ? We see that nitrogenous com- 

 pounds in general, are extremely prone to decompose : their 

 decomposition often involving a sudden and great evolution 

 of force. We see that the substances classed as ferments, 

 which, during their own molecular changes, set up molecular 

 changes in the accompanying oxy-hydro- carbons, are all 

 nitrogenous. "We see that among classes of organisms, and 

 among the parts of each organism, there is a relation between 

 the amount of nitrogenous matter present and the amount of 

 independent activity. And we see that even in organisms 

 and parts of organisms where the activity is least, such 

 changes as do take place are initiated by a substance contain- 

 ing nitrogen. Does it not seem probable, then, that these 

 extremely unstable compounds, have everywhere the effect of 

 communicating to the less unstable compounds associated 

 with them, molecular movements towards a stable state, like 

 those they are themselves undergoing ? The changes which 

 we thus suppose nitrogenous matter to produce in a body, 

 are clearly analogous to those which we see it produce out of 

 the body. Out of the body, certain oxy-hydro-carbons in con- 

 tinued contact with nitrogenous matter, are transformed into 

 carbonic acid and alcohol, and unless prevented the alcohol 

 is transformed into acetic acid : the substances formed beinsr 

 thus more highly oxidized and more stable than the substances 

 destroyed. In the body, these same oxy-hydro-carbons 

 together with some hydro- carbons, in continued contact with 

 nitrogenous matter, are transformed into carbonic acid and 

 water : substances which are also more highly oxidized and 

 more stable than those from which they result. And since 

 acetic acid is itself resolved by further oxidation into carbonio 

 acid and water ; we see that the chief difference between the 

 two cases, is, that the process is more completely effected in the 



