the nature of the stimulus, provided it was one to which the affected area had become sensitive.
By December 3 (222 days after the operation), the peculiar tingling sensation produced by cotton wool could be .evoked by stimulating the thumb and the adjoining interosseous space. This sensibility rapidly increased in extent, until there was scarcely any part of the affected area from which it could not be produced (December 6). The sensation was one which could be expressed only as a general state of diffuse painless tingling. Moreover, it was found that parts which gave this reaction to cotton wool were insensitive to No. 5 of von Prey's hairs and to the painless interrupted curi'ent, just as in the early days after the operation. Exactly the same borders could be marked out both on the forearm and hand by dragging a pin lightly from normal to abnormal parts; for as soon as the old border of cutaneous anaesthesia to touch was passed, the sensation became a widely diffused tingling pain.
Thus it would seem that the sensibility to cotton wool, which began to return to the forearm 161 days, and to the hand 224 days, after the
