CHAPTER XIV 



GENERAL APPLICATIONS OF THE NATURAL METHOD 

 OF ANALYSIS 



THE formula established in the preceding chapter, namely, 

 life is the result of a struggle between two factors, shows 

 us at once where we shall find the natural method of investi- 

 gation. 



Indeed, we have already had occasion to say : when 

 we have to study one object in reference to another object 

 with which it has relations, our method of analysis of the 

 first object must be such as to bring out precisely those of 

 its elements which are in relation with the second. 



In the present case, although life results from the struggle 

 between the two factors which we call A and B, we are 

 forced to follow out the struggle in only one of the two in 

 the body of the living individual. We have therefore to 

 study the modifications of A at each separate instant, but 

 not at random. We ought to bring out clearly the relation 

 of each modification of A to the corresponding modification 

 of B that causes it. In other words, under exterior con- 

 ditions B, when we vary experimentally some particular 

 element, it is with reference to this particular element that 

 we should study the modification obtained in A. In this 

 way we shall arrive at simple laws. 



Example : a healthy sheep is living in good hygienic 

 conditions ; into these conditions of life I introduce a new 



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