946 CUTANEOUS SENSATIONS. 



Observations by Blix 1 and Goldscheider' 2 first led to any general 

 adoption of an analysis of the sense of temperature into distinct specific 

 senses of " cold " and " warmth " respectively. These observers discovered 

 that pre-eminently at certain points of the skin a cool object evokes 

 sensation of " cold," and at certain others a warm object with special 

 facility evokes sensation of " warmth." This discovery was reached by 

 application to the skin of minutely localised stimuli, e.g. use of the 

 points of cooled or warmed metal pencils, or minute drops of ether or oil. 

 " Spots " of skin exist at which an object, very lightly applied, fails to 

 evoke the sensation of touch, but, if cold, evokes the sensation of cold ; 

 and at these points any stimulus, if sufficiently intense, evokes the sensa- 

 tion of cold. 3 Also other spots are similarly sensifacient for " warmth." 

 These "cold spots" and "warmth spots" are therefore considered, in 

 accordance with the theory of specific energies, to be the seat of specific 

 end-organs of nerves for two senses, namely, of cold and warmth. 



Weber wrote : 4 " When the hand is benumbed, there oftentimes may arise 

 from it a subjective sensation of warmth, but never, I believe, of cold." 

 Herzen 5 noted that his arm, when numbed by compression of its nerve trunks, 

 could feel warmth, e.g. the warmth of his other hand, but not cold, e.g. the 

 cold of a marble table. Faradisation of a nerve trunk evokes sensations of 

 cold and of warmth referred to the area of distribution of the nerve. 



Herzen 6 has reported the following condition of a patient (in whom post 

 mortem examination showed destruction of the dorsal columns of the spinal 

 cord and the periphery of the dorsal part of the lateral columns in the cervical 

 region) ; in the skin of the lower limbs there existed loss of tactual impressions, 

 but not of painful ; contact with objects at temperatures between 27° C. and 

 60° C. was felt, and the degree of warmth of them could be well estimated ; 

 objects at temperatures below 27° C. evoked no sensation whatever. 



Distribution of apparatus for thermal sensations in the skin, 

 etc. 1. Distribution of "cold spots" and "warmth spots." — Over 

 all the cutaneous surface of the body, when examined in areas not too 

 minute, " cold spots " much outnumber " warmth spots." Observers are 

 unanimous in finding the latter more difficult to mark and delimit. 

 The " spots " are arranged in short, slightly curved, lines, which radiate 

 from centres. These centres coincide with hairs, or, strictly speaking, 

 with the points of the surface which lie immediately over the papilla of 

 hairs. Thus it comes about that each set of lines radiates from a point 

 near the exit of a hair on the side opposite from that to which it slants. 

 The " cold spots " and " warmth spots " are usually but slightly inter- 

 spersed with each other along any individual ray, but " cold " rays and 



1 Ztschr.f. Biol., 1884, Bd. xxi. S. 152. 



2 Arch. f. Physiol., Leipzig, 1885, Suppl. S. 1. Goklscheider's discovery was made 

 before, but published after, the appearance of Blix's paper. The analysis achieved by 

 Blix and Goldscheider was clearly suspected by Czennak ("Physiol. Stud.," Wien), in 

 1855, as the result of experiments of his own. This is the more noteworthy because at 

 that date leading physiologists, including E. H. Weber, taught that even tactual and 

 thermal sensations were evoked in common from one and the same set of nerve organs and 

 fibres. E. H. Weber drew this interpretation from the fact that cold bodies feel heavier 

 than warm bodies. 



3 Goldscheider, loc. tit., v. Frey, Per. d. k. sacks. Gesellsch. d. Wissensch. zu Leipzig, 

 math.-phys. Classe, loc. cit. ; admitted in a qualified manner only by Kiesow, Phil. 

 Stud., Leipzig, 1895, Bd. xi., but reaffirmed by S. Alrtttz, Sleandin. Arch. f. Physiol., 

 Leipzig, 1897, Bd. vii. S. 321 ; denied formerly by Dessoir, Arch. f. Physiol., Leipzig, 

 1892, and Nagel, Arch. f. d. ges. Physiol., Bonn, 1895, Bd. lix. S. 570. 



4 Wagner's " Handworterbuch," Braunschweig, Bd. iii. 



5 Arch. f. d. ges. Physiol., Bonn, 1886, Bd. xxxvii. 6 Ibid., loc. cit. 



