294 Prof. C. 8. Sherrington. [ Apr. ai 
extension at elbow but flexion at elbow. That is, however, not invariable. In 
one case, in a monkey, in which the tetanus bad become general in the sense 
that only one limb was unaffected, the affected arm was strongly extended and 
rigid at elbow with some retraction at shoulder. But in all my instances 
of “ local” tetanus of the arm by introduction of the toxin into the trunk of 
the median the limb has been extended rigidly at elbow and retracted at 
shoulder. In these faradic examination of the cortex has shown that the 
small field of the “arm-area,’ to which extension at elbow is restricted, 
was enlarged so as to include the whole “ arm-area.” Extension at elbow 
sometimes alone, more often with retraction at shoulder, or with extension 
at wrist or fingers, sometimes as a leading movement, sometimes rapidly 
ensuent on retraction at shoulder or extension in the hand, according as 
higher or lower points in the area were stimulated, was prominently 
exhibited at all points of the entire surface of the “arm-area.” That area, 
with this as its salient reaction, seemed particularly excitable, for its extreme 
limits appeared traceable further than usual, and encroaching on or over- 
lapping more than is usual, under the feeble or moderate stimulation 
employed, the “leg-area” above and the “face-area” below, and to run 
exceptionally far forward above the pre-central sulcus, though remaining 
undemonstrable in the free surface of the ascending parietal convolution. 
From no point in all this extensive “arm-area” was, despite repeated trials, 
any flexion at elbow or at shoulder or hand obtained. Various intensities of 
faradisation were employed in attempt to evoke it, and points known to 
normally yield it very regularly were specially tried: but extension, not 
flexion, always resulted. 
This condition of the “arm-area” I found in experimental tetanus some- 
times exist in one hemisphere or even in both hemispheres, while the “leg- 
area” of each hemisphere yet yielded flexions at knee and hip and ankle, 
and its other normal forms of reaction. In the monkey, in my experience, 
tetanus produced by introduction of the toxin into the arm (¢g., median 
trunk) affects after the inoculated limb, the fellow fore limb first, and the 
jaw before the hind limbs, although the knee-jerk on the cel, side to 
the inoculation may be brisk. 
Under decerebrate rigidity, eg., im the cat, the closing muscles of the jaw 
are kept in tonic action, holding the mouth somewhat firmly shut.* By 
stimulation of any point of a large “ skin-area ” appropriate for the reflex, reflex 
opening of the mouth, including depression of the lower jaw is easily and 
regularly elicited. Faradisation of an afferent twig of the trigeminus produces 
* Sherrington, ‘Phil. Trans., B., vol. 190, 1898. 
