60 ADMONT H. CLARK 



posterior to the pharynx. From this node lymph vessels radiate 

 to the deep structures of the head outside of the cranial cavity. 

 A single large duct extends back to the apical node lying ventral 

 to the trapezius muscle in the posterior triangle of the neck. This 

 duct is plainly the atrophied remnant of the portion of the lymph 

 sac lying between the apex and the anterior curvature. The 

 cross connection between the apex and stalk lies along the trans- 

 verse cervical vein and joins the sac stalk near the valve into the 

 veins as in the embyro 7 cm. long. The cervical plexus, consist- 

 ing practically of large nodes, lies partly in front of the sterno- 

 cleido-mastoid muscle and partly overlaps its anterior border. 

 It is covered superficially by the panniculus carnosus muscle. 

 There are two or three large nodes in front of the ear. Eight 

 or ten ducts lead from the superficial cervical lymph nodes over 

 the sterno-cleido-mastoid muscle, and pass to the primary apical 

 node of the sac. Two or three vessels extend around the posterior 

 margin of the masseter muscle, to the submaxillary lymph glands. 

 In the injected specimens of this stage there is apparently only a 

 single large duct from the cervical plexus along the external jugu- 

 lar vein to the root of the neck. Probably there are more which 

 the injection did not reach. The retropharyngeal . and part of 

 the submaxillary vessels drain through the anterior curvature of 

 the sac and the sac stalk. The superficial vessels of part of the 

 head, the face, neck, thorax and arm drain through the superficial 

 cervical glands either to the glands of the posterior triangle or 

 directly to the sac stalk through the external jugular lymph trunks. 

 The occipital and suprascapular vessels drain through the gland 

 of the posterior triangle of the neck. 



Dissections of the adult pig show that the gland which develops 

 from the apex of the sac remains as a single gland in the posterior 

 triangle of the neck. In one specimen it measured 2 by 3 cm. 

 long. The gland from the anterior curvature of the sac also 

 remains a single gland. It is not as large as the apical gland 

 measuring 1 by 2 cm. It lies on the lateral surface of the internal 

 jugular vein just dorsal to the pharynx. No other large gland is 

 to be found along the internal jugular vein but there are a few 

 small ones. It is clear that the gland of the posterior triangle 



