SECT. XXXIX. 9. i. GENERATION. 427 



Secondly, in Mr. Buffon's theory the fetus is fuppofed to be 

 inftantaneoufly produced all at once ; whereas in our theory 

 there is believed to exift a primary, and fecondary formation ; 

 that is, that many eflential parts, as the brain and the heart, are 

 primarily produced from the congrefs of the fibrils with formative 

 appetencies, and the molecules with formative aptitudes or pro- 

 penfities ; and that thefe combinations acquire new appeten- 

 cies, and produce or unite with molecules with new aptitudes, 

 and thus generate other parts of fecondary formation, as ribs, 

 fingers, inteftines, with the external form, and the glands, which 

 conftitute the difference of the fexes. 



One great objection to the theory delivered in the former 

 part of this fection on generation is removed by this idea of the 

 exiftence of formative fibrils, and formative molecules, which 

 by their coalefcence generate various parts of the embryon at 

 the fame time ; which is, that in fome monflrous or imperfect: 

 fetufes different parts only are produced, inftead of the whole ; 

 and iuch parts as would not appear to be primary ones. Such 

 are the teeth and hair, which have been found in moles or falfe 

 conceptions, as they exift naturally at a diftance from the brain 

 and heart, which are efteemed to be the centre of vitality, and 

 are firft vifible in the embryon chick. Many other parts in 

 monflrous births are faid to have been completely formed, where 

 no brain nor heart has exifted ; the produdlion of which on oth- 

 er ideas of generation cannot be explained ; unlefs it be fup- 

 pofed, that an entire embryon had been at firft generated, all of 

 which had periftied, and had been abforbed, except the parts 

 which conftitute the monftrous or imperfect fetus at its birth, 

 which would be difficult to explain. 



Many inftances of very imperfect fetufes are recorded by 

 Monf. J. J. Sue in his Rechearches fur la Vitalite ; and in the 

 Comment, of Leipfic. I. 17. p. 528-. M. Sue differed a fetus 

 of five months old, which had no head, nor cheft, nor ftomach, 

 nor large inteftines, and yet the inferior half of the lower belly 

 was complete, with the umbilical cord, male organs of genera- 

 tion, and one complete inferior limb, of which a print is given 

 in Magazin. Encycloped. 1 797. This monftrous fetus, which 

 was only half of it formed, fhews, that the embryon is not al- 

 ways produced from one beginning, but probably from many . 

 as there was no brain or heart, the connection of nerves in the 

 lower part of the fpine muft have ferved the purpofe of the 

 former; and a junction of the large arteries and veins muft 

 have ferved the purpofe of a heart, producing a circulation like 

 that in the liver, or in the aorta and vena cava of fifb. For a 

 previous production and reabforption of the other more effen- 



tial 



