398 PHILOSOPHY OF ZOOLOGY. 



animals which produce many young at a birth, never reach 

 the uterus, but are retained in the remote extremities of 

 the horns, where they are brought to maturity. But the 

 following experiment, which has been repeated by many 

 observers, puts the subject beyond a doubt. When one 

 of the oviducts is divided, as has been tried with rabbits, 

 the corresponding ovarium, though capable of producing 

 corpora lutea, cannot generate a fetus or impregnated 

 germ *. How the sperm penetrates the small mouths of 

 the oviducts to be conveyed to the ovarium, will not likely 

 be soon determined. A small portion probably suffices to 

 produce the effect, as is known to be the case with ovipa- 

 rous animals and plants. It is not ascertained in the case 

 of those animals which produce but one at a birth, whether 

 the ovaria contribute the germs irregularly or in succession. 

 But it is probable that, in the case of twins [, and where 

 more males than one are admitted, as in the dog, both 

 ovaria contribute their share. 



* See some interesting experiments in reference to this subject by Dr 

 HAIGHTON, Phil. Trans. 1797, p, 159.; and by Mr CRUICKSHANKS, ib. 

 p. 197. 



{ There is a very curious instance of a white woman producing twins, 

 one white, and the other a negro, in Dr ELLIOTSON'S valuable Translation 

 of BLUMENBACH'S " Institutions of Physiology," p. 331." A white wo- 

 man of very gay character left her husband, and some time afterwards 

 returned pregnant to her parish, and was delivered in the work-house of 

 twins," " one of which," says Mr BLACKALLER (of Weybridge), in an 

 account which he very handsomely sent me, " was born of a darker 

 colour than I have usually observed the infants of negroes in the West 

 Indies ; the hair quite black, with the woolly appearance usual to them, 

 with nose flat and lips thick ; the second child had all the common appear- 

 ances of white children." 



Where foetuses occur with additional parts ? such as a double head, or 

 where two bodies are united at a particular part, as in the celebrated Hun- 

 garian sisters, has the monstrosity been produced by the evolution of a 

 double ovum, or by the union of two ova in the uterus ? Many circum 

 stances countenance the latter supposition. 



