ANATOMY OF THE FROG 39 



relations are exhibited in the diagram (fig. 6), in which 

 the peritoneum and the mesenterial folds are represented 

 by a broken line. The coelom, then, is a cavity which 

 contains a fluid, the peritoneal fluid, but not blood; the 

 viscera project into this cavity, but are in all cases separated 

 from it by folds of the peritoneum. The peritoneum, over 



Fig. 6. 



Diagrammatic transverse section of the body of a female Frog, 

 taken at the posterior end of the eighth vertebra, to show 

 the relation of the peritoneal membrane, represented by a 

 broken line, to the viscera. K, vertebral centrum; JVC, 

 spinal cord; n n, nerves; 6"^, the great dorsal lymph 

 spaces; Ao, aorta; / KC, interior vena cava ; K K, kidneys; 

 Ov Ov, ovaries; OdOd, oviducts; G, gut ; /, the niesen- 

 tery, a double fold of peritoneal membrane suspending the 

 gut ; 2, the mesovarium, a similar peritoneal fold suspend- 

 ing the ovary; 3, the mesometrium, a similar peritoneal 

 fold suspending the oviducts ; Ds, dorsal subcutaneous 

 lymph space ; L S, lateral subcutaneous lymph space ; l^s, 

 ventral subcutaneous lymph space. The skin is represented 

 by a thick black line. 



the greater part of the surface of the abdomen, is closely 

 adherent to its muscular walls, except for the mesenterial and 

 other folds referred to. On either side of the kidney, on the 

 dorsal side, it is separate from the muscular walls of the 

 abdomen, leaving a space, which is filled with lymph. The 

 peritoneum in the region of this space is found, on careful 

 microscopical examination, to be perforated by numerous tiny 

 apertures called stomata, putting the coelom into communica- 



