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[Vol. V. 



omphalo-mesenteric vessels, the cavities on either side communi- 

 cate by means of two quite large openings. 1 



Fig. 7 shows the gastric diverticulum somewhat more ad- 

 vanced than in Fig. 6, and resembling greatly Fig. 2. The 

 marked constriction of the connection of the diverticulum with 

 the pleuro-peritoneal cavity already marks the foramen of Wins- 

 low. A transverse section through the foramen of Winslow is 

 shown in Fie. 8. The section strikes the cceliac axis as it arises 



FlG. 8. Section through the foramen of Winslow of a human embryo 7 millime- 

 tres long. Enlarged 50 times. A., aorta; C. A., cceliac axis; S., stomach; G. D., 

 gastric diverticulum; F. IV., foramen of Winslow; P., portal vein; U., umbilical 

 vein; Z., liver. 



from the aorta. The dotted line indicates the course of the 

 hepatic artery a few sections deeper. It passes to the aboral 

 side of the foramen, and on the median side of the vein the 

 relations which are retained in the adult. 



The mesentery has become considerably larger than in the 

 dog of six millimetres or in the chick of seventy hours (Fig. 1). 

 Accompanying the increased length of the mesentery, there is 



1 A description of this embryo will be given in the next number of this Journal. 



