QUAllTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 407 



delicate membranes which every wliere cover trabeculoe of con- 

 nective tissue (endothelial membranes) ; (2) on the sarco- 

 lemma ; (3) very easily on the delicate membranes surrounding 

 primitive bundles of tendon. Thus, around each muscular 

 fibre and each primitive tendinous bundle a serous cavity can 

 be shown to exist, as has been done for nerves by Axel Key 

 and Retzius. Lowe concludes that all fibrillar connective 

 tissue is composed of membranes of the nature of serous 

 membranes, and that consequently every cavity in the tissue 

 must be viewed as a serous cavity. 



2. On the Medulla of Bone. — Robin Q Journ. de I'Anat. 

 et de la Physiol.,' Jan., 1874) has a long memoir on medul- 

 lary cells, of which, according to him, two coexistent varieties 

 may be found, the first being a complete cell, the second a 

 free nucleus, similar to the nuclei of the preceding cells. 

 These elements are always most numerous in those parts 

 in which there are few fat-cells (foetal medulla, red medullaj. 

 The size of the complete medullary cells is about that of leu- 

 cocytes, but their reactions with water and acetic acid are 

 quite different. Water does not make them paler, and only 

 causes them to swell very slightly. The granular appearance 

 is not modified, and no Brownian movement of the granules 

 is produced; their nuclei are not afiected by acetic acid. 

 Robin does not agree with Hoyer, that the capillaries, arte- 

 rioles, and venules of medulla are destitute of walls, nor does 

 he admit the opinions of Bizzozero, Monat, and Neumann, 

 who consider the medulla as an organ for the formation or 

 destruction of coloured blood-corpuscles. The first of these 

 opinions is based essentially on an identity between the me- 

 dullary cells and leucocytes, and this, according to the reac- 

 tions above given, is denied by Robin. 



4. On the Endothelium of Serous Membranes, — Tourneux 

 studied these ('Journ. de I'Anat. et de la Physiol.,' Jan., 

 1874) on newts, frogs, and toads, by the silver process. New 

 results, or rather new interpretations, are given as to the 

 relation between the peritoneal endothelium and that of the 

 cisterna lymphatica magna. The pits or depressions seen at 

 the points from which the peritoneal endothelial cells radiate, 

 and which have been considered as natural perforations 

 (stomata) in the wall of the lymphatic sac, by which it com- 

 municates with the peritoneum, are, according to him, cra- 

 teriform depressions of the peritoneum, which are occupied 

 by one or two delicate protoplasmic masses, representing endo- 

 thelial cells in their first stage of development. If these 

 young cells are partly or entirely destroyed in the preparation 

 of the object, true "perforations of the wall of the cisterna 



