242 ZOOLOGICAL PHILOSOPHY 



It appears that there is this difference between the act of fertilisa- 

 tion which prepares an embryo for the possession of hfe, and the act 

 of nature which gives rise to direct generations ; that the former acts 

 upon a small gelatinous or mucilaginous body, in which the organisation 

 was already outlined, whereas the latter is only carried out upon a 

 small gelatinous or mucilaginous body, in which there was no previous 

 trace of organisation. 



In the first case, the fertilising vapour which penetrates the embryo 

 merely breaks asunder by its expansive movement the parts which 

 in the rudiments of organisation ought no longer to adhere together, 

 and arranges them in a particular way. 



In the second case, the subtle surrounding fluids, which are intro- 

 duced into the mass of the small gelatinous or mucilaginous body, 

 enlarge the interstices within it and transform them into cells ; hence- 

 forth this small body is only a mass of cellular tissue, in which various 

 fluids can be introduced and set in motion. 



This small gelatinous or mucilaginous mass, transformed into 

 cellular tissue, may then possess life, although not yet having any 

 organ whatever ; since the simplest living bodies, both animal and 

 plant, are really only masses of cellular tissue which have no special 

 organs. On this subject, I may observe that, whereas the indis- 

 pensable condition for the existence of hfe in a body is that the body 

 shall be composed of non-fluid containing parts and of contained fluids 

 moving in these parts, the condition is fulfilled by a body consisting 

 of a very supple cellular tissue, the cells of which communicate by 

 pores : the possibihty of this is attested by the fact. 



If the small mass in question is gelatinous, it will be animal life that 

 is established in it ; but if it is simply mucilaginous, then vegetable 

 life only will be able to exist in it. 



With regard to the act of organic fertihsation, if you compare the 

 embryo of an animal or plant that has not yet been fertihsed with the 

 same embryo after it has undergone this preparatory act of life, you 

 will observe no appreciable difference between them : because the 

 mass and consistency of these embryos are still the same and the two 

 kinds of parts which compose them are extremely vaguely marked 

 out. 



You may then conceive that an invisible flame or subtle and ex- 

 pansive vapour {ovra vitalis) which emanates from the fertilising 

 material, and which penetrates a gelatinous or mucilaginous embryo, 

 that is, enters its mass and spreads throughout its supple parts, does 

 nothing more than establish in these parts a disposition which did not 

 previously exist there, break up the cohesion at the proper places, 

 separate the solids from the fluids in the way required by the 



