V 



INTRODUCTION 5 



chemical phenomena in living bodies do not confine them- 

 selves to producing chemical synthesis of extremely varied 

 substances. They organize them and render them appro- 

 priate for the morphological edification of a new being. 

 The most powerful and marvellous agent of this living 

 chemistry is, without question, the egg, the primordial cell 

 which contains the organizing principle of the whole body, 

 the germ. We cannot observe the creation of the egg ex 

 nihilo. It emanates from the parents, and the origin of its 

 evolutive potentiality is hidden from us. Science, however, 

 is bringing us every day nearer to the heart of the mystery. 

 It is by the germ, and in virtue of a kind of evolutive power 

 which it possesses, that the perpetuity of the species and 

 the descendance of beings are established. It is likewise 

 the germ which enables us to grasp the necessary Unks 

 which exist between nutritional phenomena and growth 

 phenomena. It explains, or at least allows us to conceive, 

 the limited duration of the living being. For death must 

 ensue when nutrition stops, not because food is lacking, 

 but because the evolutive sequence of an organism, which 

 must be admitted even though we do not understand it, 

 has reached the term of its career, and because the organizing 

 cellular impulse has exhausted its power. 



*The germ hkewise controls the organization of the 

 individual by forming the living substance with the help of 

 the surrounding medium, and by giving it the unstable 

 chemical characteristics which are the cause of its unceasing 

 vital movements. The cells, secondary germs, similarly 

 dominate the organization of cellular nutrition. It is 

 evident that these are purely chemical actions. But it is 

 no less evident that these chemical actions, through which 

 the organism grows and is built up, are linked together and 

 succeed each other in view of the result, which is the 

 organization and growth of the individual, animal or vege- 

 table. It is as if a vital drawing existed which traced the 

 plan of each organ, so that even though each phenomenon 

 in the organism is tributary to the general forces of nature 



