Bauhaus-Universität Weimar

nerve has no connection with the anterior motor root of the spinal 
nerves and the motor cerebral nerves. These facts, however, merely 
lead us to conclude that .the nerves of the heart as well as the nerves of 
other muscles, transmit motor influence; they still leave undecided the 
question, whether in the sound body, and in a heart removed from the 
body, the cardiac nerves are necessary for the maintenance of the con¬ 
tractile power of the organ. 
The correctness of Haller’s theory has been disputed by other physiologists,_as 
Whytt, Monro, Prochaska, Legallois, and Reil,—who contended that the motor power 
depends on a reciprocal action exerted between the nerves and muscles. Were such 
the case, the contractility of muscles would differ essentially from that of plants, 
which is excited directly by external stimuli, without the aid of nervous influence. 
In support of this opinion it is urged, that stimuli applied to the nerves excite the 
muscles to action; that narcotic substances, which seem to have a special action on 
the nervous system, when applied to the muscles, destroy their contractility; and that 
destruction of the brain and spinal cord also has the effect of diminishing the contrac¬ 
tile power of the muscles. It must, howrever, be confessed that these arguments are 
by no means weighty. The duration of the muscular irritability is not less after the 
destruction of the brain and spinal cord, than after death from other causes; and 
poisoning with narcotic substances merely causes the influence of the brain and spinal 
cord to be no longer transmitted to the muscles. The irritability of the nerves and 
muscles is far from being destroyed in frogs by narcotic poisoning: I have seen the 
usual phenomena produced by the application of stimuli to the nerves or muscles for 
a very long time in frogs thus poisoned. Treviranus has adopted a middle course 
with regard to this question; and in accordance with what is observed in plants, which 
owe their irritability to the influence of light, but yet are excitable by other stimuli, 
believes that the influence of the nerves is a necessary condition for muscular irritabi¬ 
lity, but that all stimuli do not act by their intervention on the muscles. Tiedemann 
(Physiologie, i. p. 547.—Translation by Gully and Lane, p. 295,) agrees with Haller 
in regarding the muscular contractility as a peculiar property inherent in the muscles 
themselves, but believes the maintenance of this property in them to be dependent on 
nutrition and nervous influence; and further holds that the nerves do not merely con¬ 
duct the stimulus which excites the muscular contraction, but afford an essential con¬ 
dition for the manifestation of the vital property of the muscles. This essential influ¬ 
ence of the nerves may consist either in their imparting to the muscles their property 
of being affected by stimuli, in other words, of manifesting irritability; or it may be, 
that stimuli, even when applied to the muscles, must act first upon the nerves, and 
through their medium excite the contraction of the muscular fibre. It is evident, from 
the foregoing remarks of Tiedemann, that there are here involved two perfectly distinct 
questions: 1. Is the influence of the nerves necessary for the preservation of the vital 
property of the muscles by virtue of which they contract, and is this property lost 
when the nervous influence is cut off] 2. Are the nerves conductors, through the 
medium of w’hich all stimuli act upon the muscles] does even the apparently direct 
irritation of the muscles themselves act first on the nervous fibrils distributed in the 
muscular substance, and only through the medium of them affect the contractile tissue] 
The first question may be decided in the affirmative, without the second proposition 
being necessarily admitted; but if the second receive an affirmative answer, the admis¬ 
sion of the first is a necessary consequence. 
1. Is the integrity of the nerves necessary for the preservation of the vital contrac¬ 
tility in muscles] Nystenhad observed, that, a short time after an apoplectic seizure, 
the muscles paralysed in consequence of the cerebral lesion still contracted under the 
influence of galvanism; and Wilson Philip, on the authority of Sir B. Brodie, asserted 
that a nerve, whose communication with the brain and spinal cord was cut off, retained 
for a considerable time, its faculty of exciting the muscles to contraction when irri¬ 
tated. (Phil. Transact. 1833, pt. i. p. 62.) I had reasons for suspecting that the per¬ 
sistence of this excitability of a divided nerve, when its continuity had not been re¬ 
stored by regeneration, is not without its limits; and several experiments instituted 
with reference to this question by myself, in conjunction with Dr. Sticker, (see page 
514,) have proved that, when the communication with the central organs of the nervous


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