VASCULOGENESIS IN THE CAT 11 



They were writing in refutation of Schaffer's derivation of ery- 

 throcytes from vasoformative cells and of Minot's'" expansion 

 of this obser\'ation into an absolute distinction between nucleated 

 and non-nucleated red corpuscles, and his classification of blood 

 in the vertebrates on this basis. 



Spuler showed clearly that the erythrocytes in question and 

 the vasoformative cells containing them were degenerative. 

 Fuchs, working with the omentum of the guinea pig in the first 

 few days after birth, confirmed these observations. The vaso- 

 formative cells of Schaffer" and Ranvier'^ he found usually con- 

 nected with functional vessels by narrow cell-strands, with or 

 without lumina. In a few cases the strands were interrupted. 

 This he attrilauted to rupture occasioned by unequal growth 

 in the omentum. He subscribes to the production of \'essels 

 from vasoformative cells but makes a distinction between these 

 cells and the erythrocyte containing cells which he found, as 

 Spuler had done before him, usually connected with vessels. 

 These, in view of their degeneratmg contents, may fairly be 

 deemed retrogressive. Their occasional occurrence free in the 

 connective tissue then becomes a late and not an early phase in 

 their history. The order of events in a degenerating capillary 

 would appear to be a collapse of its lumen at some intermediate 

 point or points, between or beyond which the ^'essel and content 

 persist for a time; the solidification and the reduction of the col- 

 lapsed regions to double or single rows of cells and eventually 

 long protoplasmic strands, which finally give way, and the 

 remnants of lumina with their contents of blood cells and their 

 wall of endothelium become isolated in tlie connective tissue. 

 Fuch's excellent illustrations are astonishingly like the sprouts 

 of MacC'allum and the cell cords of Bartels, differing only in 

 the cellular contents of the vessels (cf. Fuchs, fig. 2, with Bartel's 

 '09, fig. 12, and Fuch's, figs. 4, and 3, with MacCallum, figs. 6 

 and 7, respectively).. 



Identical appearances are observed in definite regions of young- 

 er embryos of the cat incident to vascular processes which are 



'» 1S90, Anat. Anz., Hd. 5, [>. SOI. " 1874, Mo. Mic. Journ., vol. 11, p. 97. 

 12 1874, Arch, cic Physiol. 



