PLATE III 



. 



EXPLANATION OF FIGURES 



34. A view of the fundus end of a vesicle which contained embryos measuring 

 31 mm. head rump length. 4 In the portion of the vesicle lying within the margin 

 of the placenta are seen four window-like spots. These are the areas where the am- 

 nia come in contact with the wall of the vesicle. The fundus end is now practically 

 free of villi. X \ 



35. A view of the cervix end of a vesicle in which the embryos measured 31 

 mm. The clear yolk-sac is seen through the opening in the rather thick placental 

 overgrowth. The margin of this opening represents the place where the placenta 

 is attached to the uterine mucosa at the cervix end of the uterus. X f 



36. The dorsal view of a vesicle which is still attached to the cervix of the con- 

 tracted uterus. This vesicle shows a distinct placental bridge (p.6.) connecting 

 the lateral placentae, and also a number of blood vessels at the fundus end. Em- 

 bryos 32 mm. in length. X f 



37. A view of the fundus end of a vesicle which contained embryos measuring 

 33 mm. This view shows two points worthy of especial note: (1) the four-lobed 

 appearance of the fundus membrane, due to constrictions occurring between the 

 fundus areas of the individual embryos (seen more clearly before fixation) ; (2) 

 the persistence of a few villi, which in the photograph appear as scattering black 

 specks. X f 



38. A view of the ventral side of vesicle, with embryos measuring 36 mm. The 

 cervix end of the yolk-sac is clearly visible, and blood vessels are seen at the fundus 

 end. The placental bridge although present is not clearly brought out in the 

 photograph. X I 



39. A view of the ventral side of a vesicle which contains embryos measuring 

 53 mm. The division of the zone-like placenta into right and left halves is clearly 

 brought out. The fundus end of the vesicle is now practically free of both villi 

 and blood vessels, and the membranous area at the cervix is much larger than in 

 the preceding figure. X 



4 Unless otherwise stated, the length of the embryo will mean the head-rump 

 measurement. 



