430 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL. VI. 
ganglion, one cannot,be sure that there are distinct granules in the cell, 
but the chromatic substance is responsible for its optical appearance, for 
the periphery of the cell is homogeneous, and does not resemble the cen- 
tral parts where we usually find the granules. The cone of origin, and 
the layer around the nucleus, described by v. Lenhossek as free of gran- 
ules, are also homogeneous. 
For observing fresh nerve cells I used the retina, because one can 
examine nerve cells in this organ more easily and more quickly than in 
any other place, and because the retina is transparent, and does not need 
to be crushed or removed from its normal medium for examination. 
The eye was generally excised immediately after death, but it was often 
half an hour before it was opened and the retina placed in some vitreous 
humour. It was laid on the slide with its nerve-fibre layer uppermost, 
and a cover slip placed upon it. Observing such a preparation, one can 
frequently detect absolutely no structure in the retina, other than the 
blood corpuscles in the vessels, even with the best lenses. After a few 
minutes, the rods and cones come into view, and then, after a consider- 
able time (sometimes an hour) the outlines of the ganglion cells appear 
but for a longer time the ceils themselves are homogeneous. Eventually 
the nuclei of these cells become visible, and still later the cytoplasm 
becomes turbid. 
One might quite as properly contend that the retina did not exist in 
life except as a homogeneous substance, and that the cells were precipi- 
tated in dying or by the fixing reagent, as that because the Nissl granules 
are not seen ina fresh condition, they are not formed elements of the 
cell. We have seen that the granules are not soluble in alkalies, so that 
argument of Held’s on the present point is valueless. 
Since it might be argued that it was one of the properties of the retina 
to be transparent the cells of the cord and cortex of young animals also 
were examined. These were killed by decapitation, the skull or verte- 
bree opened and a small piece of tissue taken and put in a drop of 
methylene blue. A cover was placed on the preparation and gently 
pressed till the latter was transparent enough for observation. The 
cells were found to have a granular appearance, resembling what 
would be found if the tissue had been fixed, embedded and stained with 
toluidin blue, and this within two minutes of death. 
Held lays stress on the fact that different fixing agents produce a 
different form of granule. It is well known that different fixing fluids 
83 Turner using methylene blue on fresh brain has observed the normal appearance of the cells shortly 
after death. ; Brain, part I, page 100, 1899, also Journal of Mental Science, 1898, 
ae 
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