362 



Dt>velo])iiu'iit of tli(> TAiiii)liatic Xoiles in tlie Pig 



lymph sac; occasionally it enters tlie surface duets that anastomose with 

 the long plexus. When the needle is introduced into the layer of the 

 lymphatics between tlie eye and ear, or over the lower jaw and front of 

 the neck, or into the pads of tlie fore feet, the injection mass runs into 



Fig. 5. Transverse section through the neck of an embryo pig, 3.6 cm. long. 

 X about 11. The shape of the entire heart of which this figure shows a 

 section is given in Fig. 4, in which the line b is the level of Fig. 5. Ca, 

 carotid artery; ejv, external jugular vein; ijv. internal jugular vein; Z, larynx; 

 Ih, lymph heart; Ip, lymph plexus along the external jugular vein; nv, vagus 

 nerve; oe, oesophagus; scm, sterno-cleido-mastoid muscle; sn, sympathetic 

 nerve. 



the long- plexus and across the sterno-cleido-mastoid muscle to the apex 

 of the lymph sac. This general relation is not only true in the stages 

 already pictured, but in the later stages when the apex of the lymph 

 heart is a lymph node and the long plexus has been replaced by a chain 

 of lymph nodes. 



