204 STUDIES IN ELECTRO-PHYSIOLOGY: 



The best illustrations I have been able to find are given 

 in Schaf er's Essentials of Histology, and I reproduce them 

 in the hope that the apparently electrical structure may 

 stimulate further research and pave the way to their 

 explanation in electrical as well as in physiological terms. 



Before doing so, however, we may usefully remember 

 that " in the ganglia each nerve-cell has a nucleated sheath 

 which is continuous with the neurilemma of the nerve-fibre 

 with which the cell is connected ; that in the spinal 

 ganglia the axis-cylinder process divides into two within 

 the ganglion, one fibre passing to the nerve-centre and 

 the other towards the periphery ; while in the sympathetic 

 ganglia the nerve-cells usually have several dendrons and 

 one axon." 



Furthermore, " the cells of ganglia are disposed in 

 aggregations of different size, separated by bundles of nerve- 

 fibres which are traversing the ganglion. The latter, if 

 large, is inclosed by an investing capsule of connective tissue 

 which is continuous with the epineurium and perineurium 

 of the entering and issuing nerve- trunks." (Schafer.) 



A peculiarity which should not be lost sight of is that 

 in the spinal ganglia and in many of the corresponding 

 ganglia on the roots of the cranial nerves of mammals the 

 only issuing process is the axon, and when this divides into 

 two the branching is T-shaped or Y-shaped, and always 

 occurs at a node ofRanvier ; the neuro-fibrils of the central 

 and peripheral branches retaining their individuality in 

 the common trunk and being traceable into a neuro-fibril 

 network within the cell body. 



And now, having collated these facts, let us remember 

 that an electrified ball exhibits the same tension on every part, 

 and see how this physical law agrees with the theory of 

 neuro- electrical cell-action, taking into consideration that, 

 while every cell in the body may be, in a sense, a condenser, 

 transmitting neuro- electrical impulses in various directions 



