r 5 ELEMENTS OF MAMMALIAN ANATOMY. 



the peritoneum and pleura; (2) minute thin-walled vessels 

 beginning by capillary mouths in the spaces just described 

 and leading to larger vessels which empty into the tracheal 

 trunks or thoracic duct; (3) the glands, which vary in size 

 from a mustard-seed to two centimeters in diameter, 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. 80). 



One of the largest of the lymphatic spaces is the greater 

 cavity of the peritoneum. The cavity of the lesser perito- 

 neum, 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 lymphatic capillaries originating in 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. 



The lymph glands (Fig. 80) of the cat are not nearly so 

 numerous as in man. The largest lymph gland is the 

 pancreas Aselli in the mesentery. It is considerably flat- 

 tened and about two centimeters long. 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 



