356 OF CONCEPTION 



stomach of the foetus, is not destined to nourish it, is 

 evident from the nature of this fluid, and from the state 

 of the chylopoietic system of the foetus : to omit argu- 

 ments deduced from acephalous foetuses, &c* 



569. The embryo, which swims in this fluid, sus- 

 pended by the umbilical chord, like fruit by its stalk, 

 begins to be formed about the third week after con- 

 ception : at first it appears of rather a globular shape, 

 resembling a little bean or kidney, from which the ru- 

 diments of the extremities grow and the face is at 

 length formed, &c.f 



570. By nature, woman is uniparous, conceiving 

 but one foetus. Frequently, however, she produces 

 twins, the proportion of which to single births, Siiss- 

 milch estimates as 1 to 704 In these cases, each 



* I trust no one will adduce in objection accounts of foetuses destitute of um- 

 bilical vessels, who has read those accounts with any attention. 



+• There is no occasion in our times to refute the false remarks and figures, 

 published by Mauriceau, Kerckring, and others, of foetuses, one or a few 

 days old. 



The reasons of my fixing upon this term, I have explained at large in the 

 Mediein. Bibliothek. vol. ii. p. 673 sq. How remarkably this was afterwards 

 confirmed by fact, will be found in the same work. vol. iii. p. 727. 



Those who have not an opportunity of inspecting the fragile primordia of our 

 race, may consult the excellent plates in Ruysch's Thetaxn. Anat. vi. tab. ij. 

 fig. 2, 3, 4, 5, 8, 10. Thesaur. x. tab iii. fig. 1. 



Also B. S. Albinus, Annotat. Acad. L. i. tab. v. fig. 4, 5. 



Tr*w, Commerc. Litter. Noric. 1739. tab. iii. fig. 4, 5. 



Abr. Vater, Mus. anatom. propr. tab. viij. fig. 2, 4, &c. 



And, equal to tliem all, Scemmerring's Jcones Embryonum Humanor. Francof. 

 ad Mcen. 1799. fol. 



X The proportion is not very constant, and is liable to national variety. (D) 



Egede expressly mentions the infrequency of twins among the Greenlanders, 

 Deter, du GrSnland. p. 112. 



Their remarkable frequency, on the contrary, among the people of Chili it 

 asserted by Molina, Saggio sur la Storia Nahirale del Chili, p. 333. 



