STRUCTURAL ALTERATIONS IN NERVE CELLS 215 
Exp. 2. Simila?- to above. Animal lived 40 da^s. 
General appearance of cells very similar to that just described above, but the powder}' blue 
appearance of the cells was more marked. 
Exp. 3. Similar to above., but animal allowed to live 100 da'^s. 
In this observation the cells much more nearl}- approached the p)'cnomorphic condition, and were 
distinctly more densely stained with the blue dye. The chromatic granules had not, however, their 
typical discrete characteristic shape, but were in a finer, more powdery condition. Occasionally a few cells 
were seen in which chromotolysis was present. There was no diminution in number of cells in the side 
of the lesion. 
In none of these observations could it be ascertained that one group of cells was more affected than 
another. The smaller cells generally appeared normal. 
Exp. 4. Human subject. Examination of the oculo-motor nucleus 18 months after enucleation of the 
eyeball. 
Microscopic examination. No difference could be noticed between the nuclei on the two sides. 
These observations indicate that there is a tendency for tlie altered cells to return to their 
normal structure independently of the regeneration of their axons, and hence confirms the opinion 
of Van Gehuchten. Chromatolysis does not therefore in general imply the death of the cell, 
but is merely the expression of its disturbed metabolism. 
The resistance of the cell varies according to its function ; thus it is asserted by Van 
Gehuchten that the cells of posterior spinal ganglion do not recover after section of their 
peripheral axis cylinders. 
Again, whilst in each of six experiments I have been able to produce changes in the spinal 
cord after division of an anterior root. Van Gehuchten,* Sano,! and MarinescoJ agree that such 
changes do not occur so readily after section of a spinal as after division of a cranial nerve. 
Yet, in certain cases the total withdrawal of the influences which normally act upon the 
cell may cause its death, as in the example quoted above by Van Gehuchten in the case of the 
oculo-motor nucleus. In this connection it may also be mentioned that Marinesco^i states that 
if the nerve is torn out, instead of being simply divided, atrophy and disappearance of the cells 
ultimately take place. The reason of this is not apparent, but his observations corroborate the 
experience of Forel, who long ago found very marked diminution in the corresponding nucleus 
after tearing the facial nerve out of the stylomastoid foramen, whilst after simple section there was 
only slight change. In my experience the ultimate fate of the cells depends not only on injury to 
the other parts of the neuron to which it belongs, but also on the extent to which the neurons in 
immediate functional relationship to it are injured. Thus in the experiment recorded in Section 
II, where both anterior and posterior roots were cut, the marked change in certain of the cells 
indicates that they at least will not recover. This also appears to be the case as the results of the 
series of experiments now to be mentioned. 
{b) Exp. i. Cat allowed to live 30 da-^s. Section of Vth, Vlth, Jllth, Vlllth posterior post-thoracic 
roots. 
The animal died from inanition ; the cord appeared to the naked e}e to be in good condition, 
and there was no trace of meningitis, but microscopical examination showed that the cells were very much 
* Van Gehuchten. La ' Presse Meciicale,' Jan. 4, 1859. \ Marinesco. 'Revue Neurologiquc,' July 30, 1898, p. 484. 
fSano. 'Journal (le Neurologie,' 1899, p. 88. § Marinesco. ' Semalne Me.licale,' 1 898, p. 108. 
