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MR. T. SNOW BECK ON THE NERVES OF THE UTERUS. 
the ganglion on passing over it ; but this is caused by gelatinous fibres, which arise 
from the ganglion, becoming associated with the tubular fibres, and passing with 
them to the lower part of the superior aortic plexus (21.21, &c.). Sometimes the 
tubular fibres and gelatinous fibres remain distinct from each other in the whole 
course of these last-named branches, so that we have a nerve whose upper half is 
white and whose lower half is gray. These branches, moreover, have a precisely 
similar constitution to that of the splanchnic nerves in the thorax, and might, not 
inappropriately, be termed abdominal splanchnic nerves. The two communicating 
branches between the spinal and sympathetic nerves are differently arranged in the 
thorax, in the abdomen, and in the pelvis. In the thorax, the branches are of nearly 
equal size through the whole extent of the cavity. In the abdomen, however, the 
gray branch is much larger than the analogous branch in the thorax, and gradually 
increases in size to the lower part of the abdomen. The white branch, on the con- 
trary, is smaller than the corresponding branch in the thorax, and decreases in size 
towards the pelvis. In the pelvis there is no white branch joining the ganglion ; and 
the branches of the sacral nerves, which might be said to represent it, pass over the 
sacral ganglia without being at all connected with them, and end in the pelvic plexus. 
The gray branch, on the contrary, is still further increased in size in the sacral region, 
and after giving some small branches to the vessels near its course, joins the sacral 
nerves. The tubular fibres found in this portion of the sympathetic, and in the 
branches which arise from it, are derived from the tubular fibres of the white branch 
from the lumbar nerves, which fibres turn down in the trunk of the sympathetic, and 
becoming associated with the gelatinous fibres form the usual sympathetic branches. 
This arrangement in the human subject corresponds with that described by Volkman 
and Bidder in the Frog*. 
19.19.19.19. Branches which pass from the abdominal sympathetic to the superior 
aortic plexus. They are composed of, part tubular, and part gelatinous fibres, in the 
same manner as the splanchnic nerves in the thorax (1 .1. and 2.2). The tubular 
fibres are derived from the lumbar nerves, and the gelatinous fibres from the abdo- 
minal sympathetic ganglia. The purpose of these branches is, moreover, similar to 
that of the splanchnic, viz. to furnish the tubular fibres which are found in the 
branches of the sympathetic. 
20.20. Small ganglia formed on these branches. 
21.21.21.21.21.21.21.21.21.21.21.21. Ganglia in the superior aortic plexus. The 
branches proceeding from the semilunar ganglion (3.3.3) to the upper part of this 
plexus are small, and few in number, and appear merely to preserve the general con- 
nexion which exists between different parts of the sympathetic. But the branches at 
the lower part of the plexus are much larger, and much more numerous, and are formed 
by the gelatinous fibres which arise from the lumbar ganglia (15.15.15), and from 
the different ganglia in the plexus (21.21.21, &c.), associated with the tubular fibres, 
* Die Selbstandigkeit des Sympathischen Nervensystems, tab. 3. 
