m 



S-VIi is the grand conclusion which immediately flows 

 from facts. 



11. The yolk has its liquors, which are conveyed to it I 

 by tlie arteries belonging to it : they circulate, and 

 without veins there -is no circulation. But the arteries 

 and veins of the yoik take -their origin from the mesen- 

 teric arteries and veins of the fetus : the heart .of this 

 latter, therefore, is' the principle of thai circulation 

 which is performed in the yolk. At the time of fecun- 

 dation the feius does not weigh the hundredth part of 

 a grain : the vorkyat that time, weighs a dram ; it has 

 vessels proportioned to its size. Now if the germ ex- 

 isted entire before fecundation, that which we stile ge- 

 neration is not the same thing with it, but is only the 

 beginning of an evolutim, which will, by degrees, bring 

 to open day such parts as were before hid in impenetra- 

 ble darkness. 



But the germ cannot be- u.) folded in an egg which 

 has not been fecundated, and incubation would only 

 accellerafc its eruption. What does it then want to 

 enable it to continue to grow 1 It has all* the organs 

 necessary for evolution. It has- even already attained 

 to a certain degree of growth, for eggs grow in young 

 pulk-ts ; their ovaries contain them of all sizes: the 

 germ grows there likewise. Why cannot it .enfold itself 

 more than it does 1 What secret force retains it within 

 the limits of invisibility ? 



Growth depends on the impulsion of the heart: a 

 greater degree of growth depends on a greater impul- 

 sion. This degree of impulsion, consequently, is want- 

 ing in the 'heart' of the germ that has not be e^ fe- 

 cundated. 



This demonstrates a certain resistance 'in the parts 

 of the germ : as it grows this resistance augments ' 

 in proportion. Some resist more than others; th& 

 berry parts, or such as will hereafter become so, more" 

 than the membranous, or those that always must . ive- 

 m&iii so. 



The heart of the germ then liaifo need of a deter- 

 ft 6- 



