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Témoignages et biographiesBiographical Memoir of M. de Lamarck, by the Baron Cuvier
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the same way that his researches on the principal facts of physics contained a 
chemistry of that character. In his opinion, the egg contains nothing prepared 
for life before being fecundated, and the embryo of the chick becomes 
susceptible of vital motion only by the action of the seminal vapour: but, if we 
admit that there exists in the universe a fluid analogous to this vapour, and 
capable of acting upon matter placed in favourable circumstances, as in the case 
of the embryon, which it organizes and fits for the enjoyment of life, we will 
then be able to form an idea of spontaneous generations. Heat alone is perhaps 
the agent employed by Nature to produce these incipient organizations ; or it 
may act in concert with electricity. M. de Lamarck did not believe that a bird, 
a horse, nor even an insect, could directly form themselves in this manner ; 
but, in regard to the most simple living bodies, such as occupy the extremity of 
the scale in the different kingdoms, he perceived no difficulty ; for a monad or 
a polypus are, in his opinion, a thousand times more easily formed than the 
embryo of a chick. But how do beings of more complicated structure, such as 
spontaneous generation could never produce, derive their existence ? Nothing ; 
according to him, is more easy to be conceived. If the orgasm, excited by this 
organizing fluid, be prolonged, it will augment the consistency of the 
containing parts, and render them susceptible of re?acting on the moving fluids 
which they contain, and an irritability will be produced, which will 
consequently be possessed of feeling. The first efforts of a being thus 
beginning to develope itself must tend to procure it the means of subsistence, 
and to form for itself a nutritive organ. Hence the existence of an alimentary 
canal ! Other wants and desires, produced by circumstances, will lead to other 
efforts, which will produce other organs : for, according to a hypothesis 
inseparable from the rest, it is not the organs, that is to say, the nature and 
the form of the parts, which give rise to habits and faculties ; but it is the 
latter which in process of time give birth to the organs. It is the desire and 
the attempt to swim that produces membranes in the feet of aquatic birds ; 
wading in the water, and at the same time the desire to avoid wet, has 
lengthened the legs of such as frequent the sides.of rivers ; and it is the 
desire of flying that has converted the arms of all birds into wings, and their 
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Auteur et directeur de publication : Pietro CORSI,
Hébergement : Centre de Calcul de l'IN2P3-CNRS.