TRANSACTIONS OF SECTION I. 781 



A Case of Paralysis of Convergence. 

 By Cyril Shaw, M.D. 



4. Determination of the Least Perceptible Tone-diff'erence among the People 

 of the Torres Straits and of Scotland. By C. S. Myers, M.A., M.D.\ 



5. Some new Features in the Intimate Structure of the Human Cerebral 

 Cortex. By John Turner, M.B. 



I. The new features referred to are : — 



(1) A beaded network enveloping the pyramidal cells of the cortex and their 

 dendrites, which although it has been seen in animals by intra-vitam staining has 

 not before been demonstrated in human beings. 



(2) An intercellular plexus of nerve-fibrils which has, I believe, not before 

 been actually demonstrated. The method employed consists in staining pieces of 

 brain tissue in a mixture of methylene blue and peroxide of hydrogen direct on 

 their removal from the body, i.e., without previous hardening or fixing. The 

 tissue is subsequently fixed in solution of molybdate of ammonia, dehydrated, 

 and cut in paraffin. 



II. The points dealt with are : — 



(1) The pericellular network. 



(2) The differentiation of the cells into pale and dark varieties. 



(3) The origin of the network from the dendrites of the dark cells. 



(4) The junction of collaterals also with the network. 



(5) The intercellular plexus of fine fibrils, 



1. The Netxuork. — It is shown to envelope the body and the protoplasmic 

 process of the pale or pyramidal system of cells, and it is not a closed structure 

 proceeding from the arborisation of a single fibre, but shows numerous delicate 

 fibrils passing to it on all sides ; and as these can be shown to proceed from 

 different cells, it follows that such cells must be in organic continuity with each 

 other. The beads on the network appear to form the nodal points for the 

 meshes. 



It is suggested that the appearance of ' thorns ' on the protoplasmic processes 

 of the pyramidal cells shown by Golgi's method is really an artefact, caused by a 

 deposition of the silver about the little tags which pass off" nearly at right angles 

 from the heads of the network, both from the cell-body and its dendrites. 



2. The Differentiation of the Cells into Pale and Dark Varieties. — The 

 pyramidal cells are very lightly stained, and as a rule their processes cannot be 

 followed far ; other cells and their processes are very darkly stained, almost 

 black in many cases. 



This division of cells is also maintained in the cerebellar cortex, where the 

 antler cells are pale and the basket and small cortical cells are dark. 



There are other distinctions 'which mark off" the two varieties, e.g., the dark 

 cells, unlike the pyramidal, show no definite orientation : they are of various shapes 

 and sizes, but are generally small and most often oval or polygonal in shape ; they 

 occur scattered about throughout the cortex, at least from the second to the fourth 

 layers inclusive, but are most numerous, roughly speaking, about the junction of 

 the outer and middle thirds of the cortex, and more numerous in the frontal and 

 occipital regions than in the so-called motor (ascending frontal) ; some of them 

 have ascending axis cylinders (Martmotti's cells), others have descending. 



3. The dendrites of the dark cells branch into AeWcaXe-beaded fibrils, and it can 

 be demonstrated that these are directly united to and in fact form the pericellular 

 network. 



