Sect. XXXIX. 5. 2. GENERATION. 405 



filament. Whereas thofe mules, where all the parts could be 

 perfectly formed, may have been produced in early periods of 

 time, and may have added to the numbers of our various fpecies 

 of animals, as before obferved. 



As this production of mules is a conftant effect from the con- 

 junction of different fpecies of animals, thofe between the horfe 

 and the female afs always refembling the horfe more than the 

 afs i and thofe on the contrary, between the male afs and the 

 mare, always reiembling the afs more than the mare ; it cannot 

 be afcribed to the imagination of the male animal which cannot 

 be fuppofed to operate fo uniformly ; but to the form of the 

 firft nutritive particles, and to their peculiar ftimulus exciting 

 the living filament to felect and combine them with itfelf. 

 There is a fimilar uniformity of effect, in refpect to the colour 

 of the progeny produced between a white man, and a black 

 woman, which, if I am well informed, is always of the mulatto 

 kind, or a mixture of the two *, which may perhaps be imputed 

 to the peculiar form of the particles of nutriment fupplied to 

 the embryon by the mother at the early period of its exiftence, 

 and their peculiar ftimulus •, as this effect, like that of the mule 

 progeny above treated of, is uniform and confident, and cannot 

 therefore be afcribed to the imagination of either of the parents. 

 Dr. Thunberg obferves, in his Journey to the Cape of Good 

 Hope, that there are fome families, which have defcended from 

 blacks in the female line for three generations. The firft genera- 

 tion proceeding from an European, who married a tawny Have, 

 remains tawny, but approaches to a white complexion ; but the 

 children of the third generation, mixed with Europeans, become 

 quite white, and are often remarkably beautiful. Vol. i. p. 112. 

 When the embryon lias produced a placenta, and furnifhed 

 itfelf with veffels for felection of nutritious particles, and for 

 oxygenation of them, no great change in its form or colour is 

 likely to be produced by the particles of fuftenance it now take3 

 from the fluid, in which it is immerfed ; becaufe it has now ac- 

 quired organs to alter or new combine them. Hence it con- 

 tinues to grow whether this fluid, in which it fwims, be formed 

 by the uterus or by any other cavity of the body, as in extra- 

 uterine geftation \ and which would feem to be produced bv 

 the ftimulus of the fetus on the fides of the cavity, where it is 

 found, as mentioned before. And thirdly, there is ftill lefs rea- 

 fon to expect any unnatural change to happen to the child after 

 its birth from the difference of the milk it now takes ; becaufe 

 it has acquired a ftomach, and lungs, and glands, of iuilicient 

 power to decompofe and recombine the milk ; and thus to pre- 

 pare from it the various kinds of nutritious particles, which the 

 appetencies of the various fibrils or nerves may require. 



From 



