18 VASCULOGENESIS IX THE CAT 



Schwann had believed that the capillaries were formed by the 

 fusion of stellate cells, and Kolliker held at first the same view, 

 but later abandoned it and considered the new formation of ves- 

 sels in the tadpole's tail wholly due to sprouting. 



Sigmund Mayer-' made an important addition to our knowl- 

 edge of the vascular sj^stem in his thorough study of its regres- 

 sive processes. He distinguished between blood containing and 

 bloodless vessels in the tadpole's tail, and pointed out that not all 

 of the latter were to be taken as Ijanphatic, for many of them were 

 degenerating blood vessels. The changes in the cu'culation in- 

 cident to their collapse supports this view. His figures show many 

 stages of their reduction and present striking resemblances to 

 those of Fuchs, MacCallum and Bartels, before mentioned. Some 

 confusion has been introduced into the terminology of these 

 structures by Miss Sabin" who has invented the term "Mayer- 

 Lewis anlage" to include these degenerating vessels and the 

 endothelial sacs described by Lewis in the course of veins in 

 the mammal. It will be remembered by the readers of F. T. 

 Lewis'" valuable paper that he found the jugular lymph sac 

 composed of several cavities, at first connected but later separated 

 from the veins. Similar sacs were found adjacent to many of 

 the veins, for which he assumed a like origin although he is most 

 careful to state that in no single instance, other than at the jugu- 

 lo-subclavian junction, was there any evidence of connection 

 with veins. 



^liss Sabin has further extended this concept to include the 

 discrete mesenchJ^llatous anlages of the hanphatics, described 

 by Huntington and McClure, which have at least a totally dif- 

 ferent structure from the formations described by Mayer. Theii* 

 walls present every degree of transition from mesenchjine to 

 full}' formed endothelium and e\-ery degree of communication 

 between their caviti(>s and the spaces in the adjacent mesench\aue. 

 They do not run off into long tapering processes, and they do 

 not contain degenerating erythrocytes. It is highlj' probable 



" ISS."), Sitz-Ber. .\kad. wiss. Wien. Bd. 91, p. ':04. 



-" 1911, .\nat. Rec, vol. .5, p. 417. 



" 1906, Arner. Jour. An.at., vol. .5, p. 95. 



