JUGULAR LYMPH SACS AND CHANNELS NECK OF PIG 57 



into the axillary vessels as can be seen in the figures from the 

 Handbuch der Entwickelungsgeschichte quoted above. The pat- 

 tern of the superficial vessels of the arm is to be seen in figure 

 5 of The American Journal of Anatomy, p. 188, volume 3, 1904. 



The mesial view is better for the lymphatics of the anterior 

 curvature of the sac. They show faintly in figure 4. Three 

 groups of vessels can be injected from the anterior curvature in 

 specimens 5 to 6 cm. long. First an abundant group which extend 

 to the wall of the pharynx, second vessels which extend along the 

 sphenoid bone to the nasopharynx and third a small chain which 

 grows outward toward the ear. It is probable that these are the 

 lymphatics for the Eustachian tube. The anterior curvature is 

 not the sole place of origin for the pharyngeal lymphatics for some 

 injections show vessels which arise from the stalk of the sac low 

 down in the neck, that is to saynearthe valve into the vein. These 

 vessels follow the course of the sac stalk, along the internal jugular 

 vein to the wall of the pharynx. Some of the pharyngeal vessels 

 anastomose with the superficial cervical plexus. Thus it may be 

 said that there is an extensive budding of lymphatics from the 

 veins of the neck. Almost all of these lymphatic buds make the 

 deep jugular sac from which vessels arise in three places (1) from 

 the apex, (2) from the anterior curvature and (3) from the stalk of 

 the sac near the valve. These latter vessels are in the main deep 

 lymphatics for the pharynx or superficial vessels which follow 

 the external jugular vein. Occasionally a vessel arises inde- 

 pendently from the external jugular vein itself. It may well be 

 brought out here that none of the injections of the deep lympha- 

 tics has ever followed the arteries or veins into the cranial cavity. 



The origin of the lymphatics of the tongue is peculiar in that 

 its vessels come from two sources. Lying beneath the mandible 

 is the submaxillary plexus, and in the posterior pharynx is the 

 retropharyngeal plexus from the anterior curvature of the sac. 

 The base of the tongue is situated between the two. Into it and 

 into the adjoining part of the pharnyx grow ducts from each of 

 these plexuses. At this stage of development the drainage is 

 probably in both directions, but as the size of the embryo increases 

 the more direct retropharyngeal route becomes the chief line, 



