406 QUARTERLY CHRONICLE OP MICROSCOPICAL SCIENCE, 



by the silver process. He found the membrana limitans 

 interna to consist of (or to have immediately in front of it) 

 a mosaic of epithelial cells. These, in the ox, are multiform, 

 fit closely into each other, forming a continuous layer over 

 the whole retina. The small spaces between the larger cells 

 are occupied by hexagonal small ones, forming a centre from 

 which the larger cells radiate. The margins of the cells are 

 irregular, but not serrated, and there are round or crescentic 

 nuclei well brought out by hsematoxylin and acetic acid. Ewart 

 also describes the lymphatic sheaths of His, as enveloping all 

 the vessels of the retina, and not only the small and medium 

 sized ones. The above-described epithelial layer could not 

 be traced beyond the ora serrata. The posterior surface of 

 the capsule of the lens is also covered by a layer of epithe- 

 lium, which in the ox consists of large polygonal cells with 

 a distinct nucleus and irregular margins, processes from one 

 cell dovetailing into those in immediate contact with it. 



2. Epithelium of the Bile-Ducts. — Ch. Legros, "Sur la 

 structure et I'epithelium propre des canaux secreteurs de la 

 bile" (* Journal de I'Anatomie,' 1874, p. 137; ' Centralblatt,' 

 1874, p. 581). 



V. Connective Tissues and Lymphatic System. — 1. On the Sub- 

 arachnoid Traheculce. — Axel Key and Retzius (' Nord. Med. 

 Arkiv.,' No. 7, 1874) describe these as consisting of fibrillar 

 connective tissue entwined by elastic fibres, and covered by a 

 cellular sheath. At the base of the brain and cerebellum 

 there are trabeculae completely enclosed in a delicate fibrillated 

 sheath, whose fibres run circularly for the most part, but 

 sometimes obliquely, forming spirals. There are also lono-i- 

 tudinal fibres in the sheath, and sometimes it is composed of 

 alternate layers of longitudinal and circular fibres with inter- 

 calated nuclei. One fibrillar sheath may enclose several con- 

 nective-tisue bundles. Acetic acid does not cause the fibres 

 of the sheaths to swell up, but, again, they are not rendered 

 more distinct, as is the case with elastic fibres. On the con- 

 trary, they become paler and less clear. These trabeculee 

 are also covered by a single layer of easily detached flattened 

 cells. 



2. Contributions to the Histology of Co7inective Tissue 



Loxve C Centralblatt,' 1874, p. 145) makes the followino- 

 statements :— Every serous membrane has two layers. The 

 superficial layer is formed of endothelial plates. The deeper 

 layer consists of a homogeneous matrix, containing flattened, 

 square, distinctly nucleated cells, arranged in regular rows! 

 If elastic fibres are present they are situated between the 

 two layers. The same structure can be shown (1) on the 



