No. 2.] THE OVARIAN EGG OF LIMULUS. 127 



3. The peritoneal coat. — As will appear more clearly in the 

 account of the developing ovary, the muscle coat of the ovarian 

 tube is surrounded by a loose coat or mantle, belonging to the 

 honeycombed peritoneal tissue. This has been mistaken for 

 the tunica propria by Kingsley ('92). It serves to suspend the 

 ovary between the carapace and the liver. This tissue is seen 

 to be laminated, and consists of greatly flattened cells, joined 

 edge to edge like the peritoneal linings of lymph spaces gen- 

 erally. The meshes of this laminated tissue appear to serve as 

 lymph sinuses, and are filled with granules and corpuscles of 

 various kinds. It is between two such lymph spaces that the 

 ovarian tube lies. The tube is organically connected with this 

 tissue along one of its sides, so as to hang suspended in a loose 

 tube, the walls of which constitute the walls of neighboring 

 lymph spaces. This peritoneal mantle or peritoneal coat of the 

 ovarian tube is comparatively loose ; and it is the looseness of 

 this coat which permits the eggs, as they develop, to push out 

 through the follicular fenestrae of the muscle coat, and to 

 occupy the space between the ovarian tube and encircling peri- 

 toneal coat. Because of its looseness, also, the ovarian tube is 

 enabled to greatly enlarge when the eggs are discharged into 

 the tube. In dissecting out the ovarian tubes, the connection 

 of the tube with this peritoneal mantle is usually severed and 

 the mantle does not appear in connection with the ovarian tube. 

 In one sense, it belongs rather to the system of lymph sinuses 

 than to the ovarian tube ; but its relation to the ovarian tube 

 is such that it serves a double purpose. The nuclei in the cells 

 of this coat are conspicuous. The corpuscles and granules, so 

 conspicuous in the lymph spaces, are not found within the 

 periovarian cavity bounded by the peritoneal coat. 



4. The lining epitJielium. — In the adult ovary, in its empty 

 and contracted state, the tunica propria becomes folded between 

 the follicles, owing to the tonicity of the muscle coat. 



The folding is especially prominent around the borders of the 

 follicles, where rachis-like projections appear to extend into the 

 lumen of the follicle. 



This folding causes a considerable lateral pressure on the epithe- 

 lial cells, which thus become greatly elongated and compressed. 



