290 OF THE FORMATION . 



cicatrice, the moment the egg iffiies from the bo- 

 dy of the hen. The heat communicated to it by- 

 incubation, expands the parts only, by putting 

 the fluids in motion. But we have never been 

 able to determine, with certainty, what parts of 

 the foetus are lirft fixed, at the moment of its 

 formation. 



I have always maintained, that the organic 

 particles were fixed, and that they united in con- 

 lequence of their motion being fufpended. Of 

 the truth of this fadt I am. fully convinced; for, 

 if the male and female femen be feparately exa- 

 mined, we find in both a great number of mo- 

 ving particles ; but, when thefe fluids are mix- 

 ed, the motion of the particles is totally deftroy- 

 ed, and a certain degree of heat is neceflary to 

 renew their activity; for the chicken, which ex- 

 ifts in the centre of the cicatrice, has no motion 

 before incubation ; and, even 24 hours, or two 

 days afterwards, when we begin to perceive it 

 without the microfcope, it has not the fmalleft 

 appearance of motion. During the firft two or 

 three days, the foetus is only a fmall white mu- 

 cilaginous mafs, which gradually acquires con- 

 fidence and magnitude. But this progrels is ex- 

 ceedingly ilow, and has no refemblance to the 

 rapid movements of the organic particles in the 

 feminal fluid. Befides, I maintained, not with- 

 out reafon, that the motion of the Organic par- 

 ticles was entirely dellroyed ; for, if eggs be 

 kept -without expofmg them to the degree of 



heat 



