DEVELOPMENT LYMPHATIC SYSTEM IN AMNIOTES 283 



form the caudal branches of the renal advehent system. The forma- 

 tion of this pair of veins produces profound changes in the post-iliac 

 spongy area. Great spaces or channels appear. These spaces seem 

 to be enormously dilated capillaries which intercommunicate with each 

 other, and connect with the accompanying veins at one or two points. 

 They contain red blood cells, and are indistinguishable from the veins 

 of that region, except by their position. They correspond to the veno- 

 lymphatics of birds and mammals. 



It is evident that Stromsten is here describing the formation 

 of early lymphatic anlages by the fusion of isolated intercellular 

 mesenchymal spaces. The resulting channels then become hae- 

 mophoric or 'veno-lymphatic/ and then establish their connec- 

 tions with the venous system. 



Stromsten lays no stress on the early phases of the intra- 

 embryonic haemopoesis, and his account does not deal with the 

 inclusion of red blood cells developed in situ within the lumen of 

 the early lymphatic channels, nor with the latter's haemorphoric 

 function in conveying these blood cells to the haemal circulation. 

 Still, his description tallies so closely with the results of Miller's, 

 West's and Allen's investigations that the presumption of iden- 

 tical genetic processes becomes more than probable. 



Fedorowicz, (30) in a preliminary communication presented to 

 the Academy of Sciences of Cracow by Hoyer on June 2, 1913, 

 deals with the early development of lymphatics in the region 

 of the caudal lymph hearts in Anura. He describes the develop- 

 ment of cell strands, on the ectal surface of the lymphatic hearts, 

 in which strands intercellular spaces appear, finally resulting in 

 the formation of an extracardial tubular structure whose lumen 

 is lined by independently developed endothelial cells. By con- 

 tinued extension of the space formation and of the endothelial 

 modification of the limiting cells, a complete lymphatic vessel 

 develops. This vessel has at first no connection with the caudal 

 veno-lymphatic heart. In the lumen of the latter, which Feder- 

 owicz regards as a dilated evagination of the lateral caudal vein, 

 similar cell strands appear, which gradually acquire a lumen, 

 by the development of intercellular spaces, and become 

 lined by endothelium developed in situ. Finally the lumina of 

 the strands developed in the later stages within the cavity of the 



