"Some deny flatly the possibility df ever arriving at 

 an understanding of the nature of life. But if we ask 

 ourselves in what this understanding of the nature of life 

 could consist, from the point of view of positive philos- 

 ophy, ive have no difficulty in recognizing that such an 

 understanding must be reduced to comparing vital phe- 

 nomena with some physico-chemical model already known, 

 suitably modified by the particular special conditions im- 

 posed upon it so that just these special conditions shall 

 determine the differences which exist between this vital 

 phenomenon and that phenomenon of the inorganic world 

 most closely related to it. If this be so, it is then the duty 

 of science emphatically to refuse to give up the attempt to 

 understand the nature of living matter, for that would be 

 to belie the Spirit of all scientific endeavor. For whether 

 it be clearly recognized or not, it is just this search for the 

 nature of the vital principle ivhich properly constitutes the 

 principal object and the final goal of all biologic study in 

 general" E. RIGNANO, in "Acquired Characters," p. 

 334- 



