. A manual of diseases of the nervous system. .; 3. ; 4. qualitative change is not always present, at any rate in recog-nisable degree. Even when there is a marked quantitative change, thekathodal closure contraction may still occur first. When the changeis present, it is only in the muscles, and it must depend on themuscular fibres themselves. In the motor nerve the kathodal responseis always the first, although a qualitative change has been detected indegenerated sensory nerves. The muscular contractions which occur thus with undue readinessdiffer from normal contracti
. A manual of diseases of the nervous system. .; 3. ; 4. qualitative change is not always present, at any rate in recog-nisable degree. Even when there is a marked quantitative change, thekathodal closure contraction may still occur first. When the changeis present, it is only in the muscles, and it must depend on themuscular fibres themselves. In the motor nerve the kathodal responseis always the first, although a qualitative change has been detected indegenerated sensory nerves. The muscular contractions which occur thus with undue readinessdiffer from normal contractions, excited through the nerves, in theirdistinctly deliberate character. Instead of the quick, lightning-likecontraction, the movement is distinctly longer in reaching its maximumand longer in its duration. This difference is very well shown in theaccompanying tracings of contraction (Fig. 37). Sometimes a slight 1. : 2. 3. 2. ; 3. : or even SYMPTOMS. 57 [or /I L JL L J\^ k JV K<i Jn Ka An Ka An Ka An Ko Aix, Ka An. Fig. 37.—Tracings of the muscular contractions in nerve-degeneration. (AfterErb.) Ka, Kathodal closure contraction; An, Anodal closure , tracing in health; £a much stronger than ^«; contractions sudden. B,tracing in nerve-degeneration with moderate current. An much greater thanKa, the latter scarcely visible. Contraction slower, shown by the moresloping upstroke. C, the same, with a stronger current. Ka greafcei, butstill less than An; the slow character of the contraction and its long durationwell marked. abnoimal tetanic contraction during the passage of the current alsooccurs. During the period of increased voltaic irritability themechanical excitability of the fibres is often increased. If they aredirectly percussed, they i-espond with a distinct slow contraction (Erb). Such are the changes in irritability which occur in cases of nerve-lesion and degeneration of moderate and considerable degrees ofseverity. Certain va
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