Page:Brain Volume 31 Part 3.pdf/37

 {| !scope=col| !scope=col| R. (sound). !scope=col| L. (affected). !scope=row| 0·025 mm. !scope=row| 0·033 mm. !scope=row| 0·041 mm.
 * Not appreciated
 * Not appreciated
 * Slightly rough
 * More definitely rough.
 * Definitely rough
 * Definitely rough.
 * }

There was no gross difference between the two sides, but, if anything, the superiority was on the side of the affected hand. On this occasion, H. dictated the following note: "When the instrument was moved across the first interosseous space, I was more certain on the left hand than on the right that it was smooth or rough. On the sound hand I was more frequently confused by the sensations which arose from the necessary contact with hairs; no such confusing accessory sensations arose on the abnormal hand. The sensation of raking was much purer on the affected side."

If the anæsthetic skin was gently lifted into a large fold, this roughness ceased to be appreciated until the projections were extended to 0·65 mm. or 0·75 mm. Even then, the "raking" was rarely appreciated, and it was doubtful whether this sensation was not due to traction communicated to deeper structures.

Thus, the power of appreciating roughness is evidently a function of deep sensibility. Complete anaesthesia of the skin, far from diminishing this sensation, seems to make its recognition slightly more easy by removing the possibility of other disturbing sensations.

Although the skin of the affected area was totally analgesic to prick and to the painful interrupted current, excessive pressure produced a characteristic aching pain over the back of the hand from the beginning of the experiment.

The first measurements with the pressure algometer were made on June 7, and resulted as follows:—

Another series gave the following results, when pressure was applied in the first interosseous space:—