106 PROCEEDINGS OF THE ANATOMICAL AND ANTHROPOLOGICAL 



EXCRETORY SYSTEM. 



The excretory system is in a very early stage of development. 

 Professor Felix of Zurich is to describe this in detail in a separate 

 paper on the development of the excretory system in early human 

 embryos. I may say that this embryo shows rudimentary pronephric 

 tubules in the region of the eighth, ninth and tenth mesodermic 

 somites, and segmental vesicles in connection with the eleventh, 

 twelfth and thirteenth segments. There is no Wolffian duct. 



CK T 



Ctv 



Anv. 



Fig. 9. Section through region of sixth somite. 

 x 50. 



Am., amnion; Sp.c., medullary canal; VI. M.S., sixth 

 somite; d.Ao., dorsal aorta; l.U.v., left um- 

 bilical vein ; CIK., ccelom ; M.G., mid-gut ; Y.S., 

 yolk sac; r.U.v., right umbilical vein; Chr., 

 chorion. 



Fig. 10. Section through region of hind 

 gut. x 50. 



Sp.c., medullary canal; Ch. , notoohord ; Am. , 

 amnion; I '.a., umbilical artery ; /.<'., um- 

 bilical veins ; A II. , allantoic duct ; B. S. , 

 body stalk; Car., ccelom ; d.Ao., dorsal 

 aorta; XI}'. M.S., fourteenth somite. 



CCELOM AND SEPTUM TRANSVERSUM. 



All parts of the coelom are in communication with each other. 

 The pericardial coelom is very large, and extends cranially on either 

 side of the median thyroid anlage. Ventrally the pericardial coelom 

 causes a bulging of the body wall, the ventricle lying in close apposition 

 with it ; while dorsally it is prolonged round into the parietal recesses 

 of His (5). Figs. 11 and 12, from a model, show the relation of the 

 umbilical vein and sinus venosus to the floor of the parietal recess, as 

 also the two horn-like extensions of the septum transversum described 



