80 BIOLOaY. [Book ii. 



We could surely in osmotic experiments draw much nearer to 

 what comes to pass in the organised bodies by making to react 

 on colloidal substances oxydant bodies, capable of giving bii-th 

 thus to crystalloidal bodies, and so on. 



The curious experiments of Traube on ai-tificial cells have 

 taught us that it is possible to imitate in a certaia measure the 

 physical and chemical phenomena of life.^ Assuredly we hither- 

 to are far from having imitated within the domain and the range 

 of the possible, the phenomena of animal physics, and jof vegetal 

 physics, which form the essence, the support of the vital acts. 

 No doubt the lack of initiative, which, in regard to this matter, 

 experimentalists have displayed, must in a large degree be at- 

 tributed to the metaphysical and mystical ideas which have been 

 conceived of life. As long as the vital phenomena were considered 

 as of an order altogether apart, as having no relation with the 

 physical or chemic3,l phenomena ; as long as there was a belief 

 that to explain what was called "the miracle of life" there had 

 to be invoked directing entities, independent of the bodies, a 

 kind of immaterial gods set over the physiological government of 

 every organism, an archeus, a vital principle, and so on, it was 

 naturally almost impossible that the idea of reproducing arti- 

 ficially the principal physico-chemical acts of life should occur to 

 experimentalists. In our days there is, foi-tunately, a complete 

 change, and we see men of science venturing on paths which they 

 would never have dreamed of entering half a century ago. 



M. Traube has based his experiments on two principal facts. 

 The first of these facts has been established by Graham ; it is, 

 that the colloids dissolved are incapable of penetrating by diffu- 

 sion through the colloidal membranes. The second fact is, that 

 the precipitates of the colloidal substances are themselves col- 

 loidal. Starting from these facts, M. Traube has been able, 

 artificially, to make cells, the wall of which was formed of 

 tannate of gelatine. He takes a drop of gelatine, which, by an 



^ Uxperimente zur Thcorie der ZellMldwng und Endosmose {ArcMv fiir 

 Anatomic, &e., von EeicUert und Dubois-Eeymond, 1867, p. 87). 



