432 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL. VI. 
stained, have observed. Dogiel,*® however, finds the cone of origin and 
axis cylinder itself are finely granular, and considers the Nissl granules 
are formed by the running together of these fine grains. Dogiel’s 
method consists in staining the fresh material in methylene blue, fixing 
in ammonium picrate, and transferring to a mixture of ammonium 
picrate in glycerine, where the tissue remains for some time, in order to 
get sufficiently transparent for examination. 
Using this method on the retina, and spinal and sympathetic ganglia, 
one obtains figures of cell-structure exactly resembling the figures of 
Dogiel. In this way spinal ganglion cells were obtained with the cone of 
origin, and the process filled with bluish-black grains resembling some of 
Dogiel’s figures. This structure must be considered entirely artificial, 
for these grains occur more or less uniformly throughout the whole 
preparation, and the examination of tissue before and after fixation 
shows that they are formed by the precipitation of uncombined colouring 
matter. Examining the cells, stained in methylene blue, but not fixed 
in the picrate, one sees they are either granular, z.e., the Nissl granules 
only are stained or they are uniformly stained, ze, the intergranular 
substance is stained as well as the granules, but if one puts the same 
cells through the fixing process, one finds fine dots of precipitated 
colouring matter all over the cells. This can be most easily followed in 
the retina, as little or no teasing of the preparation is necessary, and 
errors from that source are avoided. If one stains a retina with methy- 
lene blue, and examines it after washing as much of the colour as possible 
out of the preparation, one will find the nerve fibres are uniformly 
stained ; but, if one puts the same retina through the fixing process, and 
then examines again, one sees the nerve fibres are filled with spindles 
and round masses resembling what Dogiel figures. The same change 
may be followed in sympathetic and spinal ganglia, in which uniformly 
stained cells become covered with precipitated colouring matter in 
the process of fixation. The Nissl granules have, in the fixed prepara- 
tions, a different tint from this precipitated colouring matter, and could 
not be formed by the running together of these masses, even if the 
latter were elements of the cell. From my observations on prepara- 
tions stained by Dogiel’s process, I have concluded that his method 
is one of the best to show the morphological connections between the 
85 Dogiel, A. S., l. c. and ‘‘ Die Structurder Nervenzellen der Retina,”’ Archiv. f. Mik. Anat., XLVI, 
P. 394, 1895. : 
Also: ‘Zur Frage uber den feineren Bau des Sympathischen Nervensystems bei den Sdugethieren,” 
Arch, f, Mik, Anat., XLVI, p. 395, 1895. 
Also: “‘ Zur Frage uber den feineren Bau der Spinalganglien und deren Zellen bei Sdugethieren,” Inter. 
Monat. f. Anat. u. Phys., XIV, p. 73, 1897. 
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