144 PRACTICAL HISTOLOGY [XVIII 



to the point at which the peritoneum is seen stretching 

 from the lateral edge of the kidney to the abdominal 

 wall. Keeping the kidney lifted, so that the peritoneum 

 is kept taut, let a drop or two of '7 5 p.c. sodium sul- 

 phate run over both sides of the membrane, then, after 

 sopping up the fluid with a small piece of sponge, 

 repeat the process, but using "2 p.c. silver nitrate. In 

 3 to 5 minutes cut through the abdominal attachment 

 of the peritoneum, transfer it to sodium sulphate '75 

 p.c. (or to water), cut off the kidney. Cut the peri- 

 toneum into two unequal pieces, so that they may be 

 distinguished, and expose to light in water, one with the 

 abdominal and the other with the lymphatic surface 

 uppermost, and treat in the manner given in 1. 

 Observe on the external side, (a) the lymphatic epithe- 

 lium, consisting of large flat cells with very sinuous 

 outline, (6) the stomata, each has a small opening between 

 three or four small cells, more deeply stained than the 

 rest ; the outlines of the surrounding epithelioid cells 

 radiate from them. 



On the peritoneal side, cells less sinuous in outline 

 than the lymphatic epithelium, but more irregular than 

 the cells covering the mesentery ; stomata will also be 

 seen. (The epithelium of both sides can probably be 

 seen in the same preparation, on focussing.) 



3. Epithelioid cells of peritoneal surface of diaphragm. 

 Treat with -2 p.c. nitrate of silver (cp. 1) the peritoneal surface 

 of the diaphragm of a guinea-pig and mount, peritoneal surface 

 uppermost. Observe 



The tendon bundles of the diaphragm arranged in two layers. 

 The spaces between the bundles mark for the most part the 

 course of the lymphatic capillaries of the tendon (cp. 4). 



