118 THE NATURE AND ORIGIN OF LIFE 



body A develops and multiplies as an organ of the function 

 thus defined, so long as the sum total of conditions B which 

 define the function (A x B) remains the same. We have 

 already had examples of this law in the increased virulence 

 of victorious bacteria. 



Among the histological elements of higher animals, along 

 with those which have terminated their differential evolu- 

 tion (the constructive elements of the mechanism as a whole), 

 there are others, such as phagocytes, which are capable of 

 variation in the same way as the unicellular organisms 

 of which we have just spoken. To the latter we have to 

 apply the law of functional assimilation in the second form 

 indicated, whether the function which they exercise is 

 directly defined by a personal colloid enemy or indirectly 

 through the intermediary of the mechanism as a whole 

 constituted by the entire animal. 



In the case where the animal observed can be decom- 

 posed into tissues capable of multiplying independently 

 but without variation, the strict law of functional assimila- 

 tion leads us to apply the law of assimilation pure and simple 

 to the parts of the whole during the periods of functioning. 

 In the fifth part of this book I shall try to show that the 

 two methods of investigation employed in the third and 

 fourth parts lead to concordant results, provided only 

 we apply the language of the first method to elements 

 capable of independent multiplication, but not of varia- 

 tion elements into which we can always either effectively 

 or theoretically decompose the mechanism of the more 

 complex beings, to which the second method directly applies. 



This agreement in the results obtained by the natural 

 and the artificial methods of investigation has the very 

 great advantage of bringing into agreement the two great 

 schools of biologists that of Lamarck and that of Darwin. 



