FACTS 169 



The life of the living mass a sum of reactions passing be- 

 tween the living body and the medium is manifested in 

 every point of the protoplasmic substance, thanks to the 

 penetration by osmosis of matters taken from the medium (food 

 substances, the Q substances of our equation of elementary 

 life as manifested), and to the issuing forth, by diffusion, of 

 the R or excrementitial substances. So there is a double 

 current, ingoing and outflowing (Fig. 10), a current which 

 is invisible under the microscope, but 

 which is necessary for the constant 

 re-establishing of the equilibrium of 

 exchanges constantly destroyed by 

 assimilative reaction. We shall see 

 that the nucleus takes part in all 

 these phenomena of exchanges ; for 

 that matter, the nucleus is limited FIQ 1Q 



within the cytoplasm just as the cyto- 

 plasm is limited in the medium, and by whirlpool movement 

 of the same order. 



This exchange movement between nucleus, cytoplasm and 

 medium gives rise to a state of incessant motion whose first 

 result is to limit around the nucleus, which is itself limited, 

 the possible volume of cytoplasm mass in equilibrium. This 

 explains how growth, which is due to assimilation, is neces- 

 sarily accompanied after a certain time by a fragmentation 

 of the living mass (multiplication of bacteria, cellular 

 division). 



The system of movement determined by the exchanges 

 depends on the colloid state of the protoplasm ; and this we 

 can understand without being able to give an a priori demon- 

 stration, since we cannot define with precision the colloid 

 state. It is enough that we should understand the origin of 

 morphogenic movements ; experiments will teach us their re- 



