330 CONCLUSION 



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ponent molecules, has abandoned the geometrical shape of 



ordinary crystals and assumed the forms of granules, straight, 

 curved, and even helicoidal rods which the microbiologists 

 call micrococci, bacilli, bacteria, spirilla, etc. Elementary life, 

 from this point of view, would be nothing more than a form of 

 chemical reaction in which the living molecule, instead of 

 destroying itself by abandoning the debris to substances with 

 which it is in contact, breaks these up for its own profit and 

 increases indefinitely at their expense, not by augmenting its 

 surface volume as the crystals do, but by letting itself be 

 penetrated, and by multiplying itself by the division of its 

 mass in proportion to its growth. Nutrition would thus appear 

 to be the cause of reproduction, which assures mastery of the 

 world to organized beings which multiply by geometrical 

 progression. 



The countless variety of flowers which the horticulturists 

 can produce demonstrate that organisms are much more 

 docile than is commonly believed. It can only be the presence 

 within them of some special substances, or even of a single 

 substance, which determines the formation of these varieties, 

 and it is by no means beyond the present power of chemistry 

 to define these substances and produce them synthetically. 

 If man can work successfully along these lines, he will become a 

 creator. Henceforth the whole history of vanished organisms, 

 which palaeontology has been so painfully yet brilliantly 

 reconstructing since Professor Marcellin Boule succeeded in 

 rediscovering the entire ancestral series both of the large groups 

 and also of our present species — all this wonderful history of 

 a dimly remote past, whose first pages were deciphered by 

 Cuvier, will then receive experimental confirmation. 

 Undoubtedly the great majority of the genealogies with which 

 we must content ourselves are built up on simple hereditary 

 resemblances. As for the primitive characters whose gradual 

 modification we have observed in our reconstituted series, 

 their causes escape us completely, or can only be imagined by 

 a comparison with those we see about us. In this book we have 

 sought to place the organisms whose story we have recounted 

 in the environment where they evolved by referring, so far 

 as possible, the modifications they have undergone to the 

 conditions of their environment. These modifications result 

 partly from the direct action of physical agents such as heat, 



