90 



Florence R. Sabi 



Fig. 19. Transverse section through the pelvis of a human embryo, 80 

 mm. long. Mall collection, No. 172, to show the posterior lymph sacs, x 

 about 9. B., bladder ; Lg., lymphoglandula ; R., rectum ; S. 1. post, saccus 

 lymphaticus posterior. 



the injected pig embryos the sac seems much larger than in the 

 sections of human embryos. Its importance is that it is the anlage 

 of the visceral lymphatics ; it is transformed into the preaortic 

 nodes of which the most anterior group is around the coeliac axis. 



In Fig. 18 is shown the lower part of the cisterna chyli ; here 

 the sac is being transformed into lymph nodes while farther an- 



