74 THE NATURE AND ORIGIN OF LIFE 



We can already foresee the result of our investigation, 

 since there is an aphorism summing it up ever since Lamarck. 

 We have, indeed, been led by necessity of language to 

 define the organ by the function ; the same thing might 

 have been done for a not-living mechanism. The formula 

 " the function defines the organ " is therefore a general 

 a priori formula, which has nothing to do with biology. 

 But to the definition Lamarck added a verification the 

 expression of a fact of observation and experiment when 

 he said : 



" The function creates the organ." 



We may already divine under this very general formula the 

 law we seek the law which shall establish a relation between 

 the successive states A 2 and A! of the organism, it being 

 given that circumstances B t have determined in the individual 

 the function (A t x BJ. For a closer study of this funda- 

 mental law we must apply ourselves to the observation of 

 cases in which all things otherwise being the same we shall be 

 able to vary in the sum total B of circumstances exterior 

 to the individual a factor or a group of factors easy to deter- 

 mine and even to measure. To the variation of this factor 

 or of this group of factors we shall have to attribute the 

 modification observed in the organism we are studying. 



Before undertaking this essential study, we must bring 

 out clearly an important result of our previous deductions. 



