240 ZOOLOGICAL PHILOSOPHY 



the moment of its fertilisation, that is at the instant when by an organic 

 act it is rendered suitable for the possession of hfe, and every body 

 which derives immediately from nature the rudiments of organisation 

 and the movements of the most elementary life, are at that time 

 necessarily in a gelatinous or mucilaginous state ; although they are 

 yet composed of two kinds of parts, the one containing and the other 

 contained, the latter being essentially fluid. 



Comparison between the Organic Act called Fertilisation, 

 AND that Act of Nature which gives rise to Direct 

 Generations. 



However little we may know of the two phenomena that I am now 

 about to compare, it is quite obvious that they are related, for the 

 results accruing from them are almost identical. Indeed the two acts 

 in question both give origin to Hfe ; or give it the power of estabhshing 

 itself in bodies where it was not previously found, and which could 

 not possess it except through their agency. Thus a careful comparison 

 between them cannot but enlighten us to a certain extent on the real 

 nature of these acts. 



I have already said ^ that in the reproduction of mammals, the vital 

 movement in the embryo appears to follow immediately upon fertihsa- 

 tion ; whereas in oviparous animals there is an interval between the 

 act of fertilising the embryo and the first vital movement induced by 

 incubation ; and we know that this interval may sometimes be very 

 long. 



Now during this interval the fertilised embryo cannot yet be reckoned 

 among living bodies ; it is ready no doubt for the reception of life, and 

 to that end requires only the stimulus of incubation ; but so long as 

 organic movement has not been originated by this stimulus, the 

 fertilised embryo is only a body prepared for the possession of life 

 and not actually possessing it. 



If the fertilised egg of a fowl or any other bird is preserved for a 

 certain time without incubation or any increase of temperature, it is 

 not found to contain a living embryo ; in the same way, the seed of 

 a plant, which is really a vegetable egg, does not enclose a living 

 embryo unless it has been exposed to germination. 



Now if, owing to special circumstances, there occurs no incubation 

 or germination to start the vital movement in the egg or seed, the 

 result is that after a period, dependent on the species and the environ- 

 ment, the parts of this fertilised embryo degenerate ; the embryo, 

 since it has never actually had life, will not suffer death ; it will 



^ Recherches sur les corps vivants, p. 46. 



