XXV111 EXPLANATION OF PLATES. 



FIG. 



10. Gravid uterus of a Woman, who had committed suicide in the seventh week of preg- 

 nancy, 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 ; h, amnion ; i, umbilical vesicle ; k, umbilical cord ; 

 I, embryo; m, space between chorion and amnion (| 919-921, and 938, 939). 

 [After Wagner ("Icones Physiologic^").] 



PLATE II. 



11. Uterine Ovum of Rabbit, showing the Area Pellucida, with the primitive trace ($ 937). 



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



the dilatation of the primitive groove at its anterior extremity ($ 937). 



13. More advanced embryo, seen on its ventral side, and showing the first development of 



the Circulating apparatus. Around the Vascular Area is shown the terminal sinus 

 0, a, a. The blood returns from this by two superior branches, b, b, and two in- 

 ferior, c, c, of the omphalo-meseraic veins, to the heart, d; which is, at this period, 

 a tube curved on itself, and presenting the first indication of a division into cavi- 

 ties. The two aortic trunks appear, in the abdominal region, as the inferior 

 vertebral arteries, e, e ; from which are given off the omphalo-meseraic arteries, 

 /, /, which form a network that distributes the blood over the vascular area. In 

 the cephalic region are seen the anterior cerebral vesicles, with the two ocular 

 vesicles, g (\\ 938, 940). 

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



