JUGULAR LYMPH SACS AND CHANNELS NECK OF PIG 



55 



an area. As seen in figures 3 and 4 it is an extensive and dense 

 plexus of lymphatics lying along the external jugular vein lateral 

 to the sterno-cleido-mastoid muscle. It has in reality two points 

 of origin. First, the ventral border of the apex of the sac shown 

 in figure 2 for an earlier stage but still better in figure 3. The 

 second place of origin is a plexus of lymphatics from the stalk of 



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Fig. 4 Injected jugular lymph sac and cervical lymph plexus in a pig measur- 

 ing 7.5 cm. long, to show the relation of the developing glands in the neck to the 

 sac. Magnified 6.5 times. A .s, apex of the sac or gland of the posterior triangle of 

 the neck. The anterior curvature of the sac, which is a deep jugular pharyngeal 

 lymph gland, shows behind the sterno-cleido-mastoid muscle. C.p, superficial 

 cervical plexus which is destined to be a group of lymph glands. At the cerebral 

 end of the plexus is a developing facial gland. S.g, submaxillary lymph gland. 



