100 noTes and memoranda. 



substance of the medullary sheath. Later on every trace of 

 separation between the medullary segments disappears ; the 

 granules become larger, perhaps by confluence, so that the 

 fibres appear to be studded -with shining drops. It was, 

 unfortunately, not possible to determine whether they were 

 formed exclusively from the axis-cylinder, or were also pro- 

 ducts of the decomposition of the medullary sheath. They 

 are characteristic not only of 10% salt solution, but of all 

 liquids which harden by extracting water, and may be seen 

 in nerve kept in picric acid, 1% osmic acid, 2% chromate 

 of ammonia, alcohol, and Miiller's fluid. 



Boll draws the following conclusions from his exami- 

 nations : 



1. The axis-cylinder is liquid^ or at least semi-liquid; it 

 certainly does not possess the fibrillar structure commonly 

 assigned to it. This liquid substance is contained in a 

 special sheath. 



3. The medullary sheath is not continuous from one 

 Ranvier's node to another, but formed of a greater or less 

 number of distinct medullary segments which are, so to 

 speak, grafted on each other. Their substance is perfectly 

 homogeneous in the fresh state, and very strongly refracting. 

 The modifications induced by reagents cannot be interpreted 

 as showing a pre-existent structure. 



3. The sheath of Schwann is a completely closed tube 

 without solution of continuity. At Ranvier's nodes its sub- 

 stance is thickened in an analogous manner to the sheath of 

 connective-tissue bundles at the points of the so-called " spiral 

 fibres." — E. Klein. 



Bizzozero and Salvioli on the Structure and the Lymphatics 

 of Human Serous Membranes. — Part I. " On the Structure of 

 the Diaphragmatic Peritoneum" ('Archivio per le Scienze 

 Mediche,' vol. i, No. 3, 1876).— After referring to the de- 

 scription of Bizzozero, in 1873, of an extremely delicate 

 connective-tissue layer in human serous membranes beneath 

 the endothelium, forming a membrana limitans, the authors 

 proceed to divide the human diaphragmatic peritoneum into 

 the following layers: — 1. Endothelium. 2. jNIembrana 

 limitans. 3. Supporting layer. 4. Basement layer, or body 

 of the serosa, subdivided into a more superficial, reticular, 

 and a deeper compact portion. 5. Subserous layer. These 

 layers are not absolutely separated from each other, but are 

 joined together by a few bundles of fibrils. 



Ejidolheliuni. — Each cell forms a homogeneous jilate, to 

 which is applied the nucleus surrounded by a zone of proto- 



I 



