NEW PROCESS FOR EXAMINING THE BRAIN STRUCTURE, 187 



its peripheral process traced out, the following appearances 

 will be observed. There is a slight variation in the detail, 

 according as the cell is situated at the top or side of the 

 lamellae or at the bottom of the sulci, but the general arrange- 

 ment is as follows : — (Fig. 1.) Each cell gives off in a 

 direction toward the surface one primary trunk. This soon 

 divides into two secondary trunks which pass to the right 

 and left in a direction parallel to the surface, and in their 

 progress send off at right angles numerous branches, which 

 also are directed towards the surface or towards the pia 

 mater ; and, finally, the secondary branches, having gradu- 

 ally become smaller and smaller in their course, terminate 

 themselves by turning, like the smaller processes, towards 

 the surface. 



At each point of division there is to be observed a small 

 triangular swelling, which might aptly be compared to a 

 small blot, such as might occur when a line of ink is drawn 

 across another which is still wet. Various opinions have 

 been broached as to the nature of this swelling. Dr. Mey- 

 nert seems to have considered it due to a loose hyaline 

 sheath which he describes as investing the cells, and as 

 prolonged a short distance on the larger processes. Dr. 

 Obersteiner, on the other hand, appears to think it due to 

 the passage from one branch to another of fibres which do 

 not pass back to the cells of Purkinje, but appear, as it 

 were, to form a dii'ect outer communication between the 

 branches. I have been able to see distinctly this triangular 

 enlargement at the union of some of the finest branches, 

 such as are described below as connected with small cells in 

 the pure grey layer, and which cannot, I think, be bundles 

 of fibres, but must be single fibres. If such is the case, the 

 enlargement cannot be produced in the mode supposed by 

 Dr. Obersteiner. On the other hand, if this appearance is 

 due to a sheath, then such hyaline investment must extend 

 to the very finest fibres, and cannot cease at the point men- 

 tioned by Dr. Meynert. 



The fibres running outwards may be seen to divide and 

 subdivide into very fine branches, dividing, not three or four 

 times only, as might be supposed from the drawings given in 

 the text-books or by Dr. Obersteiner, but much more fre- 

 quently. I have observed one branch to divide more than 

 twenty-five times. 



The more distant branches are given off at very acute 

 angles, and the fibres, after a very short distance, run a 

 nearly or quite parallel course. The division is not strictly 

 dichotomous ; for in many instances small branches are given 



