14 



PHYSIOLOGY 



CHAP. 



valuable results which still constitute an important part of our 



knowledge of this subject. 



A new era in the physiology of the cutaneous senses was 



reached by the discovery of heat, cold, and pressure spots by Blix 



(1882), confirmed by Gold- 

 scheider (1883) and Donald- 

 son (1885). Another marked 

 development of the physio- 

 logy of the cutaneous senses 

 was the work of v. Frey 

 (1894-97), which showed 

 that in addition to the above 

 there also existed in the skin 

 a fourth sense-organ con- 

 stituted by pain spots. 



The work of Herzen 

 (1886) and Goldscheider 

 (1898) on the paralysis pro- 

 duced by compression of the 

 nerves of a limb also lent 

 support to the theory that 

 there are specifically distinct 

 nerves and organs of sensa- 

 tion in the skin ; sensibility 

 to cold and to pressure are 

 more strongly depressed andj 

 disappear more rapidly than/ 

 sensibility to heat and pain. 

 Ponzo (1909) showed that 

 stovaine by its peripheral 

 action produces local anaes- 

 thesia to stimuli of touch, 



FIG. 1. Thermo - aesthesiometer of Veress, seen in -nain anrl nnlrl wViilp cjpni 

 section. The instrument consists of a hollow metal P' anC 1Q > Wil] 

 cylinder 4 cm. in diameter, divided internally by a Dlllty to heat Stimuli IS re- 

 metal plate (a) into two unequal parts, into one of * i T ,-,' ,r 

 which is inserted the tube for inflow, into the other tamed. In tfllS respect the 

 that for outflow of the hot or cold water. At 6 the WQrk O f StranskyS (1899) On 



cylinder becomes conical. At c the terminal part 

 < I, is screwed on, to carry the exciting surface e, 

 which is applied without pressure on the skin. 

 The end of a thermometer hh, to measure the tem- 

 perature of the circulating water, is passed through 

 the cork which closes the top of the apparatus, 



the reappearance of sensi- 

 bility in portions of skin 

 grafted for surgical purposes 

 is of great importance. It 

 proves that tactile or pres- 

 sure sensibility appears first, while sensibility to pain and to 

 temperature develop later in the transplanted portions of skin. 



It is still uncertain whether in addition to the four modalities 

 of cutaneous sensation, viz. the sensations of contact or pressure, 

 of cold, of warmth, and of pain, other independent qualities of 

 sensation should be admitted, such as itching, tickling, sexual 



