GENERAL CONCLUSIONS 129 



indivisable unit of living matter. The " micelle" is the 

 organ of intracellular nutrition which by the stability of its 

 chemical composition and the resulting physical constitution 

 maintains the specificity of different tissues and of each 

 species and determines the cycle of evolution of each cell. 

 Separated into the salts, lipoids, and amino-acids which 

 compose it, the "micelle" no longer possesses any specificity 

 nor any of those properties which characterize living matter. 



What is the mechanism of the autoreconstruction of the 

 living "micelle?" The most recent researches mentioned 

 above oblige us to assume that animal "micelles" can assimi- 

 late untransf ormed amino-acids and they cease to live if they 

 have not certain preformed amino-acids (tryptophane) at 

 their disposal; which suggests that they are incapable of 

 constructing these substances from the simplest chemical 

 units. Van Slyke has shown that tissues absorb amino-acids: 

 the presence of amino-acids in the blood has been proved 

 by Delaunay and the works of Fischer, Kossel, and others on 

 the polypeptids permit us to conceive of the construction 

 of a biologic particle of a still more complex composition 

 and constitution. 



Is there a ferment analogous to that which hydrolyzes 

 albumins, which causes the synthesis of albumins? That is 

 hardly probable. If we imagine that a "micelle" of a certain 

 composition can attract and assimilate by a total of its 

 physicochemical properties, the amino-acids of which it is 

 composed, as a crystal attracts and fixes by analogous 

 properties molecules identical to those of which it is formed, 

 we can readily understand the autoreconstruction of par- 

 ticles of the plasma with the materials which are found in 

 abundance in the medium in which they are constantly 

 bathed: and we do not need to consider a "ferment" whose 

 existence has at the present time never been proved. 



When the "micelles" are free in a state of fluid, the colloid 

 is in the state of sol; when they are in unity in granules the 

 colloid is in the state of gel and in a living organism these 

 two states are always in unstable equilibrium; each "micelle" 

 is constantly in a state of change between gel and sol. Every 

 sudden stop, every rupture of equilibrium in this continuity 

 9 



