No. i.] 



THE LESSER PERITONEAL CAVITY. 



169 



of this relation, and on account of a similar arrangement in 

 mammals, I conclude that this constriction marks the foramen 

 of Winslow ; and I shall speak of it as such. 



On the left side (Fig. 3) the gastric diverticulum is much 



L ' aa ~ffl 



P.P. 



Fig. 3. Left gastric diverticulum of a chick, 88 hours. Enlarged 44 diameters. 

 P.P., pleuro-peritoneal cavity; L. CD., left gastric diverticulum; Z., position of 

 left lung. 



shorter and more shallow. In general, the proventriculus lies 

 on the left side of the median line, and the spaces on either 

 side seem to have taken on a corresponding shape and capacity. 

 In an embryo of five days and sixteen hours the right gastric 

 diverticulum has about doubled all its diameters, while the em- 

 bryonic foramen of Winslow has become much more sharply 

 defined (Fig. 4). At this time the liver has greatly increased in 

 size, the right lobe being larger than the left, both lying oral to 

 the foramen of Winslow. The original position of the liver 

 being aboral to the foramen, the rotation of the liver necessarily 

 carries the hepatic artery and the portal vein around the foramen 

 of Winslow, its adult position. With the growth of the gizzard, 

 a space extends from the aboral end of the right gastric diver- 

 ticulum along the dorsal side of this organ, and marks the begin- 

 ning of the cavity of the great omentum (0). Nearly the whole 



