358 



Developineut of the Lymphatic Nodes in the Pig 



The hjmpli heart. — The present paper is a continuation of two papers 

 previously presented in this journal, the first in Vol. I, 1901, and the 

 second in Vol. Ill, 190-1. It has been shown ^ that the lymphatics bud 

 off from the veins at the root of the neck, grow along the internal jugular 

 vein on either side, and expand into a sac in the neck. This sac or lymph 

 heart is shown in Fig. 1 as it appears in the neck of a pig 2.7 cm. long. 



hecn-t 



Fig. 1. Embryo pig, 2.7 cm. long, showing the anterior lymph heart in- 

 jected. X about 41/1-. E, extravasation at the point of injection; Id, lymph 

 ducts leading from the extravasation to the lymph heart. 



The lymphatics were injected with India ink by a hypodermic needle 

 introduced into the ducts over the shoulder at the point marked by the 

 extravasation in the figure. The relation of this sac to the veins is 

 shown in the accompanying diagram. Fig. 2. One duct of the sac lies- 

 along the course of the internal jugular vein. Just below the ear, under 

 cover of the sterno-cleido-mastoid muscle, this duct widens into a sac 

 which makes an arch in the neck. The sac curves outward and down- 



Ibid., Vol. I. 



