Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.

varies with the tactile sensibility of the respective regions. This power, in health, always follows the general laics of symmetry that we find governing the body. The absolute impairment of tactile sensibility may be ascer- tained by comparing a given result with the tables of Professor "Weber, which are now contained in most new books on physi- ology. Thus, if a person in health is able to recognize, as two distinct impressions at the tips of his fingers, points of only one tenth of an inch apart, it follows, that if we find him unable on one or both hands to distinguish, say more than four tenths of an inch apart, then there must be a serious impairment of nervous susceptibility to the reception or conduction of tactile impressions. The nature of the impediment must, of course, be determined by other evidences. But here it is manifest that, by applying an instrument to measure the exact tactile sensibility of differ- ent parts involved, or supposed to be involved, in a paralytic affection, we secure a more trustworthy standard, so far as it goes, to judge of the profoundness or extent and character of the affection than if we trust to the patient's description of sen- sations, or simply to the ruder mode of pricking or pinching the skin, as heretofore employed. There are three classes of circum- stances in which the aasthesioscope, or " dividers," may be use- fully employed as a help-diagnosticator : — 1. In suspected actual paralysis, to determine the amount and extent of anaesthesia. 2. As a means of diagnosis between actual paralysis of sensa- tion, and mere " subjective anaesthesia," in which case we know the tactile powers are unaltered. 3. As a means of determining the progress of any given case while under electric treatment, or where waiting for treatment, whether for the better or not. Now, it would be superfluous to give illustrations of all these three classes of cases, showing where this might afford us some assistance. The first and the third speak for themselves, and to obviate any misunderstanding of the second, an instance is subjoined.