244 1>R. O. THIN. 



succeed in isolating the developing epithelium of the young 

 capillaries, but in the new blood-vessels farmed in the inflamed 

 cornea I had better success. When the cornea had been treated 

 by osmic acid and sections disentangled with needles, the new 

 vessels were often found to be indif*ated by columns of blood- 

 corpuscles, which were adherent to isolated bands of corneal 

 tissue. When the surface of these bundles on which the 

 corpuscles lay was gently teased, cells could be isolated, 

 showing all possible degrees of transition, from the colourless 

 blood-cells to that of a fully formed epithelial cell. The first 

 stage of development consisted in the formation of a large 

 round nucleus. As the cell enlarged, the granular appear- 

 ance rapidly disappeared, and the cell could only be distin- 

 guished by the contours of the nucleus and of the cell. 



These results have been already communicated to the 

 Royal Society, in a paper now in the possession of the 

 Society, of which an abstract has been published (' Proc. 

 Royal Soc.,' No. 160, 1875). 



I have, since that memoir was written, followed M. Ran- 

 vier's studies on the development of blood-vessels in the 

 omentum of young rabbits, and the principal object of the 

 present paper is to give the results at which I have arrived, 

 after what may be described as an experimental criticism of 

 M. Ranvier's investigations. 



It is only necessary to follow M. Ranvier's simple direc- 

 tions to obtain preparations that perfectly correspond to his 

 drawings, and the most important points which he illustrates 

 and discusses may be seen by the simplest of his methods. 



A piece of the free omentum, at the pyloric end of the 

 stomach of a rabbit a month or five weeks old, is placed in 

 MuUer's fluid immediately after the animal is killed, and 

 after twenty-four hours is gently brushed on both surfaces in 

 the solution, and then washed in distilled Avater. It is finally 

 stained with picrocarminate, and immediately examined in 

 glycerine. The milky patches {taches laiteuses) of Ranvier^. 

 — the lymphatic nodules of KnaufF(' Centralblat,' No. 36, 

 1867), lymphangial nodules of Klein — can then be seen with 

 the naked eye as small red spots, and Avhen examined under the 

 microscope the cellular elements, with more or less of other 

 appearances, can be observed. 



In examining a delicate tissue like the omentum there are 

 several points that are of importance. The membrane should 

 not be allowed to shrink, nor be forcibly stretched, nor to 



1 As these patches when observed in the fresh omentum examined in 

 peritoneal serosity appear as opaque slightly raised spots, Ranvier has 

 designated them tacAes laiteuses. I prefer this term, as it implies no theory. 



