SPONTANEOUS GENERATION 243 



organisation, and dispose the two kinds of parts in this embryo for 

 the reception of the organic movement. 



Lastly, you may conceive that the vital movement, which follows 

 immediately on fertilisation in mammals but which is on the contrary 

 only set up in oviparous animals and in plants by incubation of various 

 kinds for the former and by germination for the latter, must subse- 

 quently develop by slow degrees the organisation of individuals 

 endowed with it. 



We cannot penetrate farther into the wonderful mystery of fertiUsa- 

 tion ; but the principle which I have just set forth is indisputable, 

 and rests on definite facts which I think cannot be called in question. 



It is important then to note that, in a different state of affairs, 

 nature in her direct generations imitates her own procedure for fertiUsa- 

 tion which she employs in sexual generations ; and that for this purpose 

 she does not require the assistance or produce of any pre-existing 

 organisation. 



But we must first remember that a subtle penetrating fluid in a 

 more or less expansive condition, and apparently very analogous to 

 the fluid of the fertihsing vapours, is distributed everywhere through- 

 out the earth, and that it provides and ever maintains the stimulus 

 which like orgasm is at the base of every vital movement ; so that we 

 may rest assured that in places and climates where the intensity of 

 action of the fluid is favourable to organic movement, this movement 

 never ceases until the changes which come over the organs of the Uving 

 body no longer permit these organs to lend themselves to continuous 

 movement. 



Thus in hot cUmates where this fluid abounds, and especially in 

 places where a considerable dampness acts as a co-operating agency, 

 life seems to be born and multiply everywhere ; organisation is formed 

 directly in any appropriate mass where it did not previously exist ; 

 and in those where it did exist, it develops rapidly and runs through 

 its various stages in each individual with very remarkable speed. 



It is known indeed that in very hot times and cUmates, the more 

 complex and perfect the organisation of animals may be, the more 

 rapidly does the influence of a high temperature make them traverse 

 the various stages of their existence ; this influence accelerates the 

 various stages and the termination of their Ufe. It is weU known 

 that in tropical countries, a girl becomes nubile very early, and that 

 she also reaches very early the age of decay or senility. It is, lastly, 

 an admitted fact that intensity of heat increases the danger of the 

 various known diseases, by causing them to run through their stages 

 with astonishing rapidity. 



From these principles, we may conclude that any great heat is 



