THE STRUCTURE OF THE SPINAL GANGLIA AND OF 
THE SPINAL NERVES 
S. WALTER RANSON 
Northwestern University Medical School! 
FIFTEEN FIGURES 
The application to the spinal ganglion of the reduced silver 
method of Cajal has brought to light many new facts (Cajal, ’05) 
and the renewed interest in this subject has found expression in a 
number of investigations including that of Dogiel (08). The pres- 
ent paper is concerned, in part, with a confirmation of these newer 
observations and in part with observations which, though touched 
upon by Dogiel and Cajal, escaped serious consideration by either 
of them. 
For this work the largest spinal ganglia (L vi, vii, § 1) in large 
dogs were subjected to the pyridine-silver (modified (Cajal) 
technique, an account of which has already been published (Ran- 
son, 711). Pieces of fresh nerve are placed for two days in abso- 
lute alcohol containing 1 per cent of concentrated ammonia; 
washed one to three minutes in distilled water; placed in pyridine 
for twenty-four hours, after which they are washed in many 
changes of distilled water for twenty-four hours. They are then 
placed in the dark for three days in a 2 per cent aqueous solution 
of silver nitrate at 35° C.; then rinsed in distilled water and placed 
for one day in a 4 per cent solution of pyrogallic acid in 5 per 
cent formalin. Sections are cut in paraffin and after mounting 
are ready for examination. With fresh pure chemicals, abso- 
lutely clean utensils, and a reasonably constant temperature this 
method can be relied upon to give uniform results. 
1 The work upon which this paper is based was done in the Anatomische Anstalt, 
Freiburgi. Br. My thanks are due to Professors Wiedersheim and Keibel,through 
whose courtesy it was possible for me to carry on the investigation. 
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