^32 



MODIFYING CONDITIONS. 



3. The sensibility of the limbs is finer in the transverse axis than in the long axis 

 of the limb, to the extent of th on the flexor surface of the upper limb, and th 

 on the extensor surface. 



4. The mode of application of the points of the aisthesiometer : (a) According 

 as they, are applied one after the other, instead of simultaneously, or as they are 

 considerably warmer or colder than the skin (King), a person may distinguish a 

 less distance between the points, (b) If we begin with the points wide apart and 

 approximate them, then we can distinguish a less distance than when we proceed 

 from imperceptible distances to larger ones, (c) If the one point is warm and the 

 other cold, on exceeding the next distance we feel two impressions, but we cannot 

 rightly judge of their relative positions (Czemiak). 



5. Exercise greatly improves the sense of locality; hence the extraordinary 

 acuteness of this sense in the blind, and the improvement always occurs on both 

 sides of the body ( Yolkmann). 



[Fr. C.alton finds that the reputed increased acuteness of the other senses in the case of the 

 blind is not so great as is generally alleged. He tested a large number of boys at an educational 

 blind asylum, with the result that the performances of the blind boys were by no means superior 

 to those of other boys. He points out, however, that "the guidance of the blind depends 

 mainly on the multitude of collateral indications, to which they give much heed, and not in their 

 superiority in any one of them."] 



6. Moistening the skin with indifferent fluids increases the acuteness. If, how- 

 ever, the skin between two points, which are still felt as two distinct objects, be 

 slightly tickled, or be traversed by an imperceptible electrical current, the impres- 

 sions become fused (Susloiva). The sense of locality is rendered more acute at the 

 cathode when a constant current is used (Susloiva), and when the skin is congested 

 by stimulation (Klinkenberg), and also by slight stretching of the skin (Schmey); 

 further, by baths of carbonic acid (v. Basch and v. Dietl), or warm common salt, 

 and temporarily by the use of caffein (Rumpf). 



7. Anszmia, produced by elevating the limbs, or venous hyperemia (by compress- 

 ing the veins), blunts the sense, and so does too frequent testing of the sense of 

 locality, by producing fatigue. The sense is also blunted by cold applied to the 

 skin, the influence of the anode, strong stretching of the skin, as over the abdomen 

 during pregnancy, previous exertion of the muscles under the part of the skin 

 tested, and some poisons, e.g., atropin, daturin, morphin, strychnin, alcohol, 

 potassium bromide, cannabin, and chloral hydrate. 



Millimetres. 



Tip of tongue, . . . . 1-1 [11] 

 Third phalanx of finger, volar 



surface, 2-2*3 [17] 



Red part of the lip, . . . 4 5 [3*9] 

 Second phalanx of finger, volar 



surface 4 -4 '5 [3*9] 



First phalanx of finger, volar 



surface, 5-5*5 



Third phalanx of finger, dorsal 



surface, 6 "8 [4*5] 



Tip of nose, . . 6*8 [4*5] 

 Head of metacarpal bone, volar, 5-6-8 [4*5] 

 Ball of thumb, .... 6*5-7- 

 Ball of little finger, . . 5 5-6- 

 Centre of palm, . . 8*-9* 

 Dorsum and side of tongue, white 



of the lips, metacarpal part of 



the thumb, . . . . 9' [6*8] 

 Third phalanx of the great toe, 



plantar surface, . 11*3 [6*8] 

 Second phalanx of the fingers, 



dorsal surface, 113 [9] 



Back, 11-3 [9*] 



volar 



toe, 



Millimetres. 

 11*3 [9*] 

 13*5 [11*3] 



Eyelid, 



Centre of hard palate, 



Lower third of the fore-arm 



surface, . 

 In front of the zygoma, 

 Plantar surface of the great 

 Inner surface of the lip, 

 Behind the zygoma, . 

 Forehead, ... 

 Occiput, ... 

 Back of the hand, 

 Under the chin, . 

 Vertex, 

 Knee, 



Sacrum, gluteal region, 

 Fore-arm and leg, 

 Neck, 

 Back at the fifth dorsal vertebra, 



lower dorsal and lumbar region, 

 Middle of the neck, . 

 Upper arm, thigh, and centre of 



the back, . . . 677 [31*6-40*6] 



15* 



15-8 [11-3] 

 15*8 [9*] 

 20*3 [13*5] 

 22*6 [15*8] 

 22-6 [18*] 

 27*1 [22*6] 

 31*6 [22*6] 

 33*8 [22*6] 

 33*8 [22*6] 

 36*1 [31*6] 

 44*6 [33*8] 

 45*1 [33*8] 

 54*1 [36*1] 



54*1 

 677 



