SPONTANEOUS GENERATION 239 



indirect part in the existence of all other living bodies, since they are 

 all derived one after the other from the original individuals ; mean- 

 while in the course of long periods, she wrought changes and an increase 

 of complexity in their organisation, and ever preserved by reproduction 

 the modifications acquired and the development attained. 



If it is admitted that all natural bodies are really productions of 

 nature, it must be quite clear that in bringing the various Hving bodies 

 into existence, she must necessarily have begun with the simplest, that 

 is with those which are in truth the veriest rudiments of organisation 

 and which we scarcely venture to look upon as organised living bodies. 

 But when by means of the environment and of her own powers, nature 

 has set going in a body the movements constituting life, the repetition 

 of these movements develops organisation in it and gives rise to nutri- 

 tion, the earliest of the faculties of life ; from the latter soon arises the 

 second of the vital faculties, namely, growth of the body. 



Excess of nutrition in causing growth of this body prepares in it 

 the material for a new being with a similar organisation ; and thus 

 provides it with the power to reproduce itself. Hence originates the 

 third of the faculties of hfe. 



Finally, the continuance of life in a body gradually increases the 

 hardness of its containing parts and their resistance to the vital move- 

 ments : it proportionally enfeebles nutrition, sets a Umit to growth, 

 and finally compasses the death of the individual. 



Thus as soon as nature has endowed a body with life, the mere 

 existence of life in that body, however simple its organisation may be, 

 gives birth to the three faculties named above ; and its subsequent 

 stay in this same body slowly works its inevitable destruction. 



But we shall see that life, especially in favourable conditions, tends 

 incessantly by its very nature to a higher organisation, to the creation 

 of special organs, to the isolation of these organs and their functions, 

 and to the division and multipUcation of its own centres of activity. 

 Now since reproduction permanently preserves all that has been 

 acquired, there have come from this fertile source in course of time 

 the various living bodies that we observe ; lastly, from the remains 

 left by each of these bodies after death, have sprung the various 

 minerals known to us. This is how all natural bodies are really pro- 

 ductions of nature, although she has directly given existence to the 

 simplest Hving bodies only. 



Nature only establishes life in bodies that are at the time in a 

 gelatinous or mucilaginous state, and that are sufficiently soft to respond 

 easily to the movements which she communicates to them by means 

 of the exciting cause that I have spoken of, or of another stimulus 

 which I shall hereafter endeavour to describe. Thus every germ, at 



