THE ACTIONS OF FORCES ON ORGANIC MATTER. 39 



sufficient to make the next, also, fall from unstable to stable 

 equilibrium. Now since, among mingled compound mole- 

 cules, no one can undergo change in the arrangement of its 

 parts without a molecular motion that must cause some dis- 

 turbance all round; and since an adjacent molecule dis- 

 turbed by this communicated motion, may have the arrange- 

 ment of its constituent atoms altered, if it is not a stable 

 arrangement; and since we know, both that the molecules 

 which are changed by this so-called catalysis are unstable, and 

 that the molecules resulting from their changes are more 

 stable; it seems probable that the transformation is really 

 analogous, in principle, to the familiar one named. Whether 

 thus interpretable or not, however, there is good reason for 

 thinking that to this kind of action is due a large amount of 

 vital metamorphosis. Let us contemplate the several groups 

 of facts which point to this conclusion.* 



In the last chapter (§2) we incidentally noted the extreme 

 instability of nitrogenous compounds in general. We saw 

 that sundry of them are liable to explode on the slightest 

 incentive — sometimes without any apparent cause; and that 

 of the rest, the great majority are very easily decomposed by 

 heat, and by various substances. We shall perceive much 

 significance in this general characteristic when we join it 

 with the fact that the substances capable of setting up exten- 

 sive molecular changes in the way above described are all 

 nitrogenous ones. Yeast consists of vegetal cells containing 



* On now returning to the subject after many years, I meet with some 

 evidence recently assigned, in a paper read before the Royal Society by Mr. J. 

 W. Pickering, D.Sc. (detailing results harmonizing w^ith those obtained by 

 Prof. Grimaux), showing clearly how important an agent in vital actions is 

 this production of isomeric changes by slight changes of conditions. Certain 

 artificially produced substances, simulating proteids in other of their charac- 

 ters and reactions, were found to simulate them in coagulability by trifling 

 disturbances. " In the presence of a trace of neutral salt they coagulate on 

 heating at temperatures very similar to proteid solutions." And it is shown 

 that by one of these factitious organic colloids a like effect is produced in 

 coagulating the blood, to that " produced by the intravenous injection of a 

 nucleoprotcid." 

 4 



