200 ELEMENTARY PHYSIOLOGY. [XVIII. 



C. Lymphatic Capillaeies. 



The lymphatic trunks need not be noticed, since 

 their structure is essentially the same as that of 

 the veins. (Lesson xn.) 



1. From a frog remove the intestines (and if neces- 

 sary the oviducts) as in Lesson x. E. It will be 

 seen that the peritoneum above and to the 

 outside of the kidney is not adherent to the 

 lumbar muscles, but is separated by a space — the 

 cistern a magna lymphatica. Turn the frog over, 

 raise the vertebral column near its end with 

 forceps, cut it through; cut through the abdomi- 

 nal walls parallel to the vertebral column and 

 about half an inch from it, taking care not to 

 injure the underlying peritoneal wall of the 

 eisterna ; cut through the vertebral column about 

 an inch in front of the first cut ; the dorsal sur- 

 face of the peritoneal cisternal wall will now be 

 seen attached to the kidneys in the median line 

 and to the abdominal walls laterally. Place a 

 ring of cork underneath the kidneys and attached 

 membrane and cut through the abdominal wall 

 close to the edge of the membrane, inserting a 

 hedgehog quill after each cut to keep the mem- 

 brane flat but not tense. Having thus separated 

 the membrane, stream it gently with salt solution 

 then very briefly with distilled water, imme- 

 diately after this pour on both sides of it a little 

 nitrate of silver solution 0"o p.c. (or place it in 

 the solution) and leave it for five to ten 

 minutes. Wash it well with distilled water, and 



