578 SENSATIONS OF TEMPERATURE. [Boon in. 



was felt, though the application of the same spoon at the 

 temperature of the body produced no sensations, and yet the 

 heated spoon was not recognised as a hot body but appeared 

 to be simply something touching the skin. It may be argued 

 that these instances shew nothing more than the changes in 

 the skin whatever they be, which give rise to sensations of 

 pressure, are modified by the temperature of the skin for the time 

 being, whereby the judgment as to the pressure which is being 

 exerted is rendered faulty ; but they may also be taken to indicate 

 that variations in pressure and temperature affect the same 

 terminal organs, and the same nerve-fibres, though affecting them 

 in a different way and generating nervous impulses so far different 

 that they give rise to different sensations. And we may here note 

 that we certainly cannot speak of nerves of warmth in the same 

 sense in which we speak of nerves of sight or of hearing. A 

 stimulus (of whatever kind) applied to an optic or auditory 

 nerve, if adequate, gives rise, as we have seen, to a sensation of 

 light or of sound; a stimulus, on the other hand, applied to the 

 trunk of a cutaneous nerve gives rise only to general feeling or 

 pain; though the nerve certainly contains fibres by which sen- 

 sations of pressure and of temperature reach the brain, the general 

 feeling which stimulation of the trunk causes is akin neither to 

 sensations of pressure nor to those of warmth. 



The rapidity with which hot or cold bodies brought into contact 

 with the skin give rise to sensations of temperature, suggests that the 

 terminal apparatus for generating these sensations, whatever be its 

 nature, is placed in the epidermis, and indeed as near as possible to 

 the surface. Pressure on the other hand can be readily transmitted 

 through even a thick layer of skin. And those who maintain the 

 existence of different terminal organs for pressure and temperature, 

 regard the nerve-endings in the epidermis as the latter and the 

 corpuscula tactus, end-bulbs and allied organs as the former. But 

 the evidence we possess concerning this matter is at present incon- 

 clusive. 



