XVI EXPLANATION OF PLATES. 



FIG. 



9. Portion of the mucous laj-er of the germinal membrane, highly magnified ; show- 

 ing that it is made up of cells, whose borders are more distinct and more 

 closely applied to each other than those of the serous layer, and whose con- 

 tents are more transparent ($ 776). 



[The six preceding figures are after Bischoff (Entwickelungsgeschichte der 

 Saugethiere, etc. (1842), des Kaninchen-eles (1842) des Hunde-eies 

 (1845).] 



10. Gravid Uterus of a Woman who had committed suicide in the seventh week of 

 pregnancy, laid open : a, os uteri internum ; b, cavity of the cervix ; c, c, c, 

 c, the four flaps of the body of the uterus turned back ; d, d, d, inner surface 

 of uterine decidua; e, e, decidua reflexa; /, /, external villous surface of the 

 chorion ; g, internal surface of the chorion ; A, amnion ; i, umbilical vesicle ; 

 k, umbilical cord ; I, embryo ; m, space between chorion and amnion ( 752 

 et seq.). [After Wagner (Icones Physiologicce).~\ 



PLATE II. 



11. Uterine Ovum of Eabbit, showing the Area Pellucida, with the primitive trace 



(3 776). 



12. More advanced Ovum, showing the incipient formation of the Vertebral column, 



and the dilatation of the primitive groove at its anterior extremity ( 776). 



13. More advanced Embryo, seen on its ventral side, and showing the first develop- 



ment of the Circulating apparatus. Around the Vascular Area is shown the 

 terminal sinus a, a, a. The blood returns from this by two superior branches 

 b, b, and two inferior, c, c, of the omphalo-mesaraic veins, to the heart, d 

 which is, at this period, a tube curved on itself, and presenting the first indi- 

 cation of a division into cavities. The two aortic trunks appear, in the ab- 

 dominal region, as the inferior vertebral arteries, e, e ; from which are given 

 off the omphalo-mesaraic arteries/,/, which form a network that distributes 

 the blood over the vascular area. In the cephalic region are seen the ante- 

 rior cerebral vesicles, with the two ocular vesicles, g (\ 777). 



[The three preceding figures are from the works of Bischoff previously cited.] 



