Bauhaus-Universität Weimar

13Ô 
EXPERIMENTS ON THE 
nerve retained its irritability for a certain period, still, if the union of 
the two portions were prevented, the irritability was afterwards lost; 
so that when at the end of two months the galvanic stimulus of a sin¬ 
gle pair of plates was applied to the lower portion of the nerve, it 
produced no contractions in the muscles to which the nerve was dis¬ 
tributed. Even when applied to the muscles themselves, the galvanic 
stimulus in several cases did not excite contracfion. The experiments 
on rabbits made by me, are, therefore, more in favour of the supposi¬ 
tion of reproduction of the nerve than opposed to it. In the third ex¬ 
periment only the irritability in the lower part of the nerve was 
almost completely lost, (although the nerve was allowed to unite,) 
and in this case, therefore, it seems that the nerve had cicatrised, but 
that the nervous communication was not restored. Since it appears 
from Sticker’s experiments that, unless their communication with 
the brain and spinal cord is maintained, nerves cannot preserve their 
irritability for any length of time, the mere fact that the lower por¬ 
tion of a divided and reunited nerve is irritable after the lapse of 
several months, proves that the union of the nerve restores in some 
degree the nervous communication. 
Schwann has recently performed an experiment, which clearly 
proves the fact of the reproduction of nerves in the frog:—He divided 
the ischiadic nerve in the middle of both thighs; after the operation, 
the frog at first leaped but rarely, generally moving only by crawl¬ 
ing; after a month it leaped more frequently, and at the end of 
three months this movement was performed almost as well as by 
any other frog. By the aid of the microscope, however, the now 
united nerve, at the place of division, was seen to contain nervous 
fibrils, lying close together and running its whole length, and the 
transparent aspect seemed to result only from the neurilema being 
less perfectly reproduced. The fibrils were continuous with those 
of the two ends of the nerve, and the stretching that was necessary 
for the microscopic examination fully accounted for the nervous 
cylinders being, at some points, connected only by very delicate 
threads. The upper end of the nerve was enlarged, as is the case 
with the ends of nerves in the stump of an amputated limb; the 
lower portion did not present the same appearance. The nerve of 
the other side could not be examined. The fact of the reproduction 
of the nervous fibres after the removal of a portion of a nerve has 
been confirmed by Steinrück. (Froriep’s Notiz. Dec. 1838.) 
Without the reproduction of the nervous substance which has been 
thus demonstrated by Schwann, the experiments of Haighton, Pré¬ 
vost, and Tiedemann are inexplicable. Tiedemann divided in a dog, 
the nerves of the fore-foot and leg, namely, the ulnar, radial, median, 
and external cutaneous nerves, in the axilla, and at the expiration 
of eight months observed a return of sensation and motion, which 
was still greater after twenty-one months; and at last the dog re¬ 
gained the complete use of the foot. This experiment is most con¬ 
vincing with reference to regeneration of nerve. The return of 
some degree of sensation in transplanted flaps of skin, even after the 
division of the portion by which it was connected to its original
        

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