XVIII] LYMPHATIC SYSTEM 149 



cavity of an anaesthetized rabbit. In three to four hours the animal 

 is killed by bleeding, the surface of the diaphragm washed with salt 

 solution, and strong spirit poured over it. In about 5 minutes the 

 abdominal viscera are removed, the thorax opened, the diaphragm 

 pinned out on a piece of cork, removed from the body and placed in 

 strong alcohol. Pieces of the tendon are mounted in balsam. 



If the tongue of a frog is drawn out, a lymph sac on its (then) 

 dorsal surface is generally distinct. The sac can readily be distended 

 (a) with the aid of a Pravatz syringe, or glass rod drawn out to a fine 

 point ; the skull and upper part of the spinal column being first cut 

 away ; (6) by forcing fluid into the dorsal lymph sac. The thin 

 membrane bounding it can be cut out and the epithelium of the outer 

 surface removed by scraping; its inner surface treated with silver 

 nitrate shows large epithelioid cells ; it can also be used to show very 

 fine fibrous tissue imbedded in ground substance, and a plexus of 

 branching striated muscle fibres. 



