ON THE FUNCTIONAL ACTIVITY OF NERVE CELLS. 719 



previously to the commencement of meduUation in the cervical sym- 

 pathetic nerve, I found later a smaller number of fibres medullated 

 upon the cut side, and also many atrophied cells in the ganglion ; but in 

 a third experiment, in which longer time had elapsed since the section of 

 the same branches, there was little, if any, difference in the two cervical 

 sympathetic nerves. I have therefore made other experiments to decide 

 what are the results following section of post-ganglionic fibres, but the 

 experiments are not yet complete. 



The section of the cervical sympathetic nerve in a young kitten 

 appeared to have little, if any, effect upon the development of the superior 

 cervical sympathetic ganglion. 



In the cord of a kitten 120 days old, in which part of the cervical 

 sympathetic nerve had been removed on the eighth day after birth, I 

 found that the small cells in the lateral horn of the first, second, and 

 third dorsal segments upon the cut side were very decidedly fewer in 

 number than upon the uncut side. I have twice repeated this experi- 

 ment, but the spinal cords have not yet been examined. 



Some of my experiments by the atrophy method point clearly to the 

 correctness of Mott's hypothesis, that cells of Clarke's column are con- 

 nected with afferent nerve fibres supplying the lower limb. 



A preliminary account of some of the observations made has been 

 given in a thesis for the M.D. degree at Cambridge, and it is hoped that 

 fuller details may soon be published. 



V, The Histology of Nerve Cells. By GusTAV Mann, M.D. 



Over seventy different fixing methods were used, and chemically most 

 diverse substances chosen so as to eliminate, if possible, all appearances 

 due to arte facts. Reducing and oxidising, acid, neutral, and alkaline 

 fixations, acid, neuti-al and alkaline stains, with reducing and oxidising 

 substances added, were tried, and these results were obtained : — 



(1) In all nerve cells there exists a peripheral zone, destitute of Nissl's 

 bodies, and in this zone numerous fibrils and bundles of fibrils are seen. 



(2) The zone-like origin of the axis cylinder is due to a special 

 accumulation of the plasm constituting the peripheral zone. 



(3) At the periphery of nerve cells the fibrils were not observed to 

 branch. 



(4) Bundles of fibrils run also through the centre of cells, past the 

 nucleus, but the fibrils never come into contact with Nissl's bodies. 



(5) In spinal ganglia two distinct bundles of fibrils may be dis- 

 tinguished, one corresponding to the peripheral and the other to the 

 central process. These bundles are arranged in vortices. 



(6) In central and peripheral multi-polar nerve-cells bundles of fibrils 

 may be traced from dendritic processes to the axis- cylinder process, and 

 from one dendritic process to another. 



(7) The thorn-like excrescences seen in Golgi preparations are arte- 

 facts, caused by the potassium bichromate. 



(8) The nodes of Ranvier are only crossed by the neuro-fibrils. 



Photographs of wax models were taken, and the course of the fibrils 

 traced in the following cells : Two giant cells of Malapterurus, motor cell 

 from anterior horn of spinal cord of the ox, spinal ganglion cells of rabbit 

 and dog, cell from spiral ganglion (cochlea) of guinea-pig, first giant cell 

 of Amphioxus, sympathetic nerve-cell of rabbit. Photographs of nerve- 



