COMPARATIVE AND HISTORICAL. 421 



separated by a thin membrane, perforated with stomata, from the abdominal 

 cavity. This is the cysterna lymphatica magna of Panizza. Some amphibians and 

 many reptiles have large lymph-spaces under the skin, which occupy the whole of 

 the dorsal region of the body. All reptiles and the tailed amphibians have large 

 elongated reservoirs for lymph along the course of the aorta. The lymph apparatus 

 of the tortoise (Fig. 159) is very extensive. 



The osseous fishes have in the lateral parts of their backs an elongated lymph- 

 trunk, which reaches from the tail to the anterior fins, and is connected with 

 the dilated lymphatic rootlets in the base of the tail and in the fins. The largest 

 internal lymph-sinus is in the region of the cesophagus. Many birds possess a 

 sinus-like dilatation or lymph-space in the region of the tail. The lymph-spaces 

 communicate with the venous system with valves properly arranged usually 

 in connection with the upper vena cava. Lymph-hearts have already been 

 referred to (p. 417). 



In carnivora, the lymph-glands of the mesentery are united into one large com- 

 pact mass, the so-called " pancreas Asellii." 



205. Historical. 



Although the Hippocratic School was acquainted with the lymph-glands from 

 their becoming swollen from time to time, and although Herophilus and Erasis- 

 tratus had seen the mesenteric glands, yet Aselli (1662) was the first who accur- 

 ately described the lacteals of the mesentery with their valves. Pecquet (1648) 

 discovered the receptaculum chyli ; Rudbeck and Thorn. Bartholinus the lymphatic 

 vessels (1650-52) ; Eustachius (1563) was acquainted with the thoracic duct, which 

 Gassendus (1654) maintained that he was the first to see; Lister noticed that the 

 chyle became blue when indigo was injected into the intestine (1671) ; Sommering 

 observed the separation of fibrin when lymph coagulated; Reuss and Emmert 

 discovered the lymph-corpuscles. The chemical investigations date from the first 

 quarter of this century ; they were carried out by Lassaigne, Tiedemann, Gmelin, 

 and others. The two last observers noticed that the white colour of chyle was 

 due to the presence of small fatty granules. 



