FACTS 207 



For many very temporary modifications it is probable that 

 the organism behaves like a spring. A man bent beneath 

 the weight of a burden stands up when he has laid it down 

 and takes his normal form ; but if every day, during several 

 hours, he remains bent, he will finally take the bend. The 

 general equilibrium of the body certainly feels this ; but 

 we wish to know whether the egg, which shares in this 

 modified equilibrium, is strongly enough impressed to carry 

 with it, outside of the body which gave the impression, 

 the corresponding modification ; or whether it, too, will not 

 relax its tension like a spring and cease being subject to 

 the cause of variation. 



So the problem is two-fold ; 



1. Has the cause of action B acted long enough for the 

 body of the animal to keep the trace of it ? 



2. If the animal preserves the trace, has the egg remained 

 long enough in relation of equilibrium with the animal for 

 it to keep the impression when it issues from the animal ? 



Evidently, only in this latter case can the acquired 

 character become hereditary. There is always the dove- 

 tailing of our mechanisms : the anatomic mechanism of the 

 animal is moved by the conditions of the environment ; 

 it influences secondarily the equilibrium of the animal's 

 colloid mechanism ; and this, thirdly, may influence in its 

 turn the chemical mechanism. Then the character will 

 be very profoundly acquired, and, in such a case, the rever- 

 sibility of chemico-physical phenomena on one side and the 

 morpho-biological theorem on the other will enable us to 

 make the following assertion : 



" The modification transmitted to the hereditary patri- 

 mony of the egg will manifest itself in the next generation 

 by a descriptive character of the same order as that which 

 had been directly produced in the parent. Thus, in terms 



