922 CUTANEOUS SENSATIONS. 



bristle) 1 is perceptible. These spots are called "touch spots." In a square 

 centimetre of such skin the touch spots are about fifteen in number. If 

 into one of these " spots " a fine needle be thrust, there is excited a strong 

 sharply localised sensation of pressure, unaccompanied by smart or sting 

 or any painful quality. Goldscheider 2 describes the impression as having 

 a " shotty " character, as of a little hard body embedded in the skin, and 

 there pressed upon. The sensation is unaccompanied by " cold " or 

 " warmth," even when a cold or warm needle is employed. 



Almost invariably there are one or more " touch spots " close to the 

 place of emergence of each hair ; they lie usually on the side from which 

 the hair slopes. It is usual for " touch spots " to be arranged in short 

 lines, radiating from the mouth of a hair follicle. In an area of the fore- 

 arm (back) containing fifteen hairs, Goldscheider figures seventy-eight 

 " touch spots " ; also, on the flexor aspect, 147 " touch spots " to twenty- 

 two hairs ; and sixty-six " touch spots " to thirty-eight hairs in a small 

 area of the scalp. In hairless regions which compose about one-fiftieth 

 of the total body surface of man the " touch spots " also lie in short 

 chains radiating from certain points. 



The " touch spots " are much more numerous in some regions than in 

 others. An area of the dorsum of the ungual phalanx of a finger con- 

 tains about seven times as many as an equal area from between the 

 shoulders. Kegions comparatively poor in " touch spots " are the flexor 

 aspect of the upper arm, the upper third of the thigh, the leg above the 

 inner malleolus, the neck, and in general the skin over subcutaneous 

 surfaces of bone. In some of these regions, roughly oval intervals, 

 measuring a centimetre along the major axis, exist between the 

 individual " touch spots." 



Neither are all regions of skin equally freely furnished with " touch 

 spots," nor do some regions contain any purely tactual apparatus at all, 

 if we agree to sunder from pure " touch " the sensations which are 

 elicitable from " pain spots." It is obvious that as there are scattered 

 upon the cutaneous surface sensory end-organs of four different functional 

 groups, e.g. touch, cold, warmth, and pain, the organs of these four 

 classes can be in different regions commingled in different proportions. 

 Nowhere are touch organs the only end-organs present, nor are they in 

 any region interspersed with only one other of the three remaining kinds 

 of sense spots. Together with " cold spots " and " warmth spots," they 

 contribute to a ternion combination for the surface of the cavity of the 

 mouth ; throughout that cavity pain spots are few, and from certain 

 parts of the inside of the cheek are wanting altogether. 3 Elsewhere 

 the touch organs where they occur lie commingled with individual 

 organs of all three of the other kinds. But they do not occur in quite 

 all the mucous and cutaneous regions in which representatives of the 

 other kinds are present. They are absent from the cornea 4 and con- 

 junctiva of the upper lid, 5 and from the glans penis. 6 



1 v. Frey, "Beitr. z. Sinnesphysiol. d. Haut," Ber. d. k. sacks. Geselhck. d. Wissensch. 

 z. Leipzig, math.-phys. Classe, July 1894, Dec. 1894, March 1895, August 1897. 



2 Arch. f. Physiol., Leipzig, 1885, Suppl., S. 11. 



3 Kiesow, Phil. Stud., Leipzig, 1893, Bd. ix. S. 510 ; Arch. ital. dc liol., Turin, 1897, 

 tomo xx vi. ; v. Frey, Ber. d. Jc. sacks. Gcsellsck. d. Wisscnsch. zu Leipzig, matk.-pkys. 

 Classe, loc. cit. 



4 Hoggan, Linnean Soc. Journ. ZooL, London, vol. xvi. p. 82 ; v. Frey, loc. cit. 



5 v. Frey, loc. cit. Nagel says they are very few, Arch. f. d. ges. Physiol., Bonn, 1895, 

 Bd. lix. S. 570. 



6 v. Frey, loc. cit. 



