422 



OTTO F. KAMPMEIER 



Fig. 3 Transverse section through the region just in front of the mesonephroi 

 in a 19 mm. embryo (series 168, slide 23, section 17), X 150. 6c, supracardinal 

 periaortic veno-lymphatics in the positions of the later right and left thoracic 

 ducts; lid, lis, right and left postcardinals; 12d, 12s, right andleft supracardinals; 

 13, aorta; 17, oesophagus. (Reconstructions, figs. 28 and 32.) 



duction of the most posterior segment of the thoracic duct, or 

 cisterna chyli, they may be labelled posterior supracardinal 

 veno-lymphatics. 



Situated topograpically in the pathway of the future thoracic 

 duct, all of the veno-lymphatics mentioned in the three divisions 

 would be said to give rise to it directly, or to be transformed into 

 it, were the second or transition phase of its history disregarded. 

 This leads up to the suggestion that Lewis' and temporarily also 

 McClure's multiple endothelial-lined anlagen derived from the 

 veins along which they lie are nothing more and nothing less than 

 the veno-lymphatics or precursors of the thoracic duct as deline- 



