The Lymphatic System in Human Embryos. 



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tive sciatic veins and inferior vena cava. It measures 4.6 x .5 x .96 

 (dorso-ventral), and runs almost to the cisterna chyli, with which 

 a connection cannot be made out. The plane of the Sicction, coronal, 

 is not especially advantageous for determining whether the connection 

 has been made or not. 



Fig. 14. Coronal section through the jugular lymph sac of the same 

 embryo, at the level shown in Fig. 21, to show the simple bridging of 

 the sac which is the anlage of the first lymph node. X about 19. S. 1. j., 

 saccus lymphaticus jugularis. 



The jugular sacs show a number of points of interest. First 

 their increase in size, this being the stage of the maximum size. 

 The valve is very beautifully shown, as is seen in Fig. 13. The 

 level of this section is shown on the diagram. A second point of 

 interest is the extensive bridging of the sac. This occurs especially 

 near the dorsal border, as is shown in Fig. 14. At this stage the 

 bridges of connective tissue, which cut the sac, show more connective 



