SECT. 87.] MUSCULAR SYSTEM. 163 



Dtichenne, that in atrophied muscles no longer obeying the will, 

 the atrophy may be corrected by the employment of galvanism 

 regularly continued, so that, finally, such muscles again become 

 subject to the will. If the statement of Duchenne be confirmed, 

 that the same thing may, in some measure, be effected in muscles 

 which have ceased to contract when stimulated by galvanism, it 

 seems difficult to avoid the conclusion, that in these cases the gal- 

 vanism acts directly on the muscular fibres, and, by in some way 

 affecting their nutrition, renders them capable of again performing 

 their functions. 



The muscles .also possess sensibility, but of a peculiar kind, inas- 

 much as punctures, burns, and cuts of their substance do not 

 occasion notable pain; whilst, on the other hand, all muscles are 

 painful after long-continued action, or when affected with cramp, 

 and become very sensitive to pressure. They also possess a very 

 fine sensation of their own condition of contraction, and very slight 

 variations in the force exerted by them may be discriminated. 

 This apparent contradiction is explained by the fact, that the 

 muscular nerves contain but few sensitive fibres, as may be easily 

 demonstrated in the nerves of the ocular muscles for instance. 

 These fibres, to which those above- described as scantily distributed 

 over the whole muscle probably belong, are too sparing in numbers 

 to make a muscle sensitive to local influences, but suffice, when 

 they are implicated by the contraction of the whole muscular mass, 

 to convey to the sensorium a notion of the degree of pressure 

 which they suffer, and, in over-exerted muscles, to occasion pain, 

 in consequence of the oft-repeated irritation, or of the compression 

 they undergo from rigidity of the muscles. 



In investigating the muscles, it is necessary to study them in the fresh 

 condition, and also when treated with various re-agents. Muscular Jibres are 

 most readily isolated in muscles which have been boiled, or preserved in 

 alcohol, on which, also, the transverse striae are very beautiful ; likewise after 

 treatment with corrosive sublimate or chromic acid. For the study of the 

 transverse striae, it is, moreover, indispensable to examine muscles in various 

 conditions of extension and contraction. The observation of the first point 

 is highly instructive, and may be easily carried out by examining a thin, 

 slender muscle, such as the hyo-glossus of a frog in different degrees of 

 tension, upon an object-plate of wood, with an opening in the middle filled 

 up with glass. With this arrangement, it may be seen that when the muscle 

 is in no degree stretched, the transverse striae are fine (o - ooo4"') and very 

 close to each other, and the fibres broad. Under full extension, on the 

 other hand, the striae are o - ooo8'" broad and the same distance from each other, 

 and the fibres narrower. The contractions are to be examined in fresh, still 

 quivering muscles, moistened with serum, albumen, or vitreous humour ; or 



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