THE VASCULAR SYSTEM 1 83 



eter, and are located chiefly on the side of the neck, in the 

 axillary region, at the bifurcation of the trachea; in the inguinal 

 region, lumbar region, and mesentery; (4) the two tracheal 

 trunks and thoracic duct (Fig. 91). 



One of the largest of the lymphatic spaces is the greater 

 cavity of the peritoneum. The cavity or the lesser peritoneum, 

 a large lymphatic space, may be shown by separating the layers 

 of the great omentum carefully. The cavity of the pleura 

 within the chest is also a large lymphatic space. Numerous 

 small lymph spaces are present in all parts of the body. The 

 beginnings of lymphatic capillaries draining these spaces are 

 invisible to the naked eye, but their union into larger vessels 

 may be demonstrated satisfactorily in a cat just killed, by 

 pulling forward the tongue, and injecting very slowly beneath 

 the skin, on its ventral aspect five or ten centimeters of a two 

 per cent, solution of Berlin blue in warm water. A very good 

 demonstration of the thoracic duct may be had by feeding the 

 cat a half pint of milk about two hours before killing, or by using 

 Gage's method described on page 13. 



The lymph glands (Fig. 91) of the cat are not nearly so 

 numerous as in man. The largest lymph glands is the mesen- 

 teric lymph gland in the mesentery. It is considerably flat- 

 tened and about two centimeters long. It is formed by the 

 grouping of several smaller glands and was formerly known as 

 the pancreas Aselli. A few other very small lymphatic glands 

 are also present in the mesentery. The two largest lymph 

 glands of^ the head are just beneath the skin craniad of 

 the submaxillary gland. On the side of the neck beneath the 

 cephalohumeral muscle are three large lymph glands at the 

 cranial border of the scapula. A small axillary gland lies on 

 the caudal side of the axillary vein beneath the scapula. A 

 single popliteal gland is in the popliteal space, an inguinal gland 

 lies on each side of the penis, two or three iliac glands are near 

 the origin of the femoral artery, and a few small lumbar glands 

 lie in the lumbar region of the abdominal cavity. 



