GANGLION CELLS. 131 



water to wash away what remains of the acid, and 

 then glycerine to preserve the preparation, after 

 winch the edges of the cover-glass may be cemented. 

 Besides the nerve-cells, which in a carefully-prepared 

 specimen may be very well seen, with their long 

 branching processes extending in some cases far be- 

 yond the field of the high power objective, some 

 points in the structure of the nerve-fibres of the 

 spinal cord can be well made out in these prepara- 

 tions. For example, it may be readily seen that the 

 medullary sheath has broken away in many parts 

 from the white nerve fibres, and where not actually 

 removed has become swollen and coagulated in 

 irregular masses around the axis cylinder, changes 

 which could hardly have taken place were there any 

 structure surrounding the nerve fibres such as the 

 primitive sheath of the peripheral nerves. Further, 

 where the axis-cylinders are in this manner laid bare, 

 as they often are for a considerable part of their 

 length, their fibrillar structure can, with a high 

 power, be made out without difficulty. A similar 

 structure can also he seen in the processes of the 

 nerve cells, and extending from them through the 

 body of the cell itself. 



Preparation 6. The cells from the ganglia, 

 whether spinal or sympathetic, are isolated in a 

 manner similar to that employed in the case of the 

 spinal cord, except that the period of maceration in 

 the bichromate solution needs to be longer, owing 

 to the much larger amount of connective tissue by 

 which the nervous elements are invested. At the 

 same time it is quite possible to get a certain number 

 of the cells sufficiently isolated, even from the fresh 

 ganglion, without any maceration; for each cell 

 being loosely contained in a special capsule of flat- 

 tened cells, it readily falls out when the nerve fibres 

 with which it is connected are ruptured. But 

 although the cells themselves of the ganglia are 

 readily enough separated, it is very difficult, both 

 in the fresh and in the macerated preparations, to 



