442 Helen Willistoii Smith. 



His describes a human embryo in which the membrana reiiniens 

 contains vessels emptying into the sinus reuniens above, and into the 

 umbilical vein below. This is a condition found in pig embryos 

 of about 7 mm. and one that is easily interpreted by a study of 

 younger and older stages. This observation is confirmed and ex- 

 tended by Mall, who says, 'Tt appears, then, that during the third 

 week of development, while the umbilical veins still empty into 

 the sinus reuniens, an extensive plexus is formed throughout the 

 greater extent of the membrana reuniens, which receives blood from 

 the aorta on its dorsal side, and empties into the umbilical vein 

 on its ventral side. As the umbilical vein changes its position to enter 

 the liver, this circulation through the membrana reuniens is broken 

 up as a much earlier circulation through the umbilical vesicle was 

 broken up." 



Kolliker and Coste give a description of a somewhat older type. 

 Kolliker pictures a cow's embryo in which the membrana reuniens 

 is filled with a minute plexus radiating from the myotomes to the 

 umbilical vein, and Wertheimer quotes Coste as follows, speaking 

 of the vessels in the abdominal wall of the adult: "Ces vaisseaux 

 sont les restes du riche appareil veineux transitoire, qui des parois 

 abdominales sur lesquelles ils etaient repandus, se portent vers la 

 veine ombilicale ou allantoi'dienne droit dans laquelle ils penetrent 

 par une foule de troncs, place les uns a cote des autres. Ils suivent 

 la destinee de la veine qui les regoit et s'eteignent completement 

 avec elle." 



That I am correct in naming the vessel described above as the 

 thoraco epigastric is evident upon comparison with the thoraco 

 epigastric in the human adult. This is a vein subject to consider- 

 able variation, and described somewhat differently in the text-books. 

 Toldt and Spalteholz and Piersol describe it as extending subcu- 

 taneously from the superficial epigastric vein, on the anterior and 

 lateral surface of the trunk, to enter the long thoracic. Sabotta 

 says it may either enter the long thoracic or the axillary vessel 

 directly. In this laboratory I have examined a number of cadavers 

 which show variations, agreeing for the most part with the two 

 types given by Sabotta. The thoraco epigastric vein is unques- 



