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nerves and ganglions in producing animal heat. 
in the nerves that supply the electric organs ; each of these 
nerves arises separately from the brain, and consists of nu- 
merous fasciculi. 
yours, &c. 
Ci^:SAR HAWKINS.^' 
From Mr. Hawkins's examination the ganglions in the 
skate do not amount to one-sixth part of those in the bird, 
and the standard heat of this fish is low in proportion ; the 
thermometer in the stomach being only 40°, in the rectum 
38®, while the surrounding water was 36°. 
. EXPLANATION OF PLATE XVII. 
In which is exhibited the external and internal appear- 
ance of the great splanchnic ganglion. 
Fig. 1 . The ganglion in situ upon the aorta ; natural 
size. 
Fig. 2. The ganglion enclosed in its outer or dura matral 
covering ; magnified two diameters. 
Fig. 3. A longitudinal section ; magnified in the same 
degree. 
Fig. 4. A small portion from which the outer or dura 
matral covering has been removed, but is still inclosed in 
the inner or pia matral coat ; magnified six diameters. 
Fig. 5. A longitudinal section ; magnified in the same 
degree. 
Fig. 6 . A very small portion of the internal substance of 
the ganglion ; magnified twenty diameters, to show that it 
consists of fasciculi of globular fibres from to 
part of an inch in diameter, similar to those in the brain, 
connected together by a transparent elastic jelly : this jelly 
MDCccxxv. N n 
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