PHYSIOLOGY OF MAN. 



CHAPTER I. 



SPECIAL SENSES TOUCH, ETC. 



General characters of the special senses Muscular sense (so called) Apprecia- 

 tion of weight Sense of touch Variations in tactile sensibility in different 

 parts Table of variations measured by the aesthesiometer Connection be- 

 tween the variations in tactile sensibility and the distribution of the tactile 

 corpuscles Titillation Appreciation of temperature Venereal sense. 



OUR study of the nervous system, in the volume devoted 

 to that subject, has involved simply motion and what is 

 known as general sensibility ; and almost all our positive 

 knowledge of these properties has been derived from experi- 

 ments upon the inferior animals. As regards sensation, the 

 experiments have referred to impressions recognized as pain- 

 ful ; and we have seen that these are conveyed to the centres 

 by nerve-filaments, anatomically as well as physiologically 

 distinct from those which convey to the contractile parts the 

 stimulus that gives rise to motion. As far as we have studied 

 the sensory nerves, we have alluded to simple impressions 

 only ; but it is evident that the filaments of peripheral distri- 

 bution of these nerves are capable of receiving a variety of 

 impressions, by which we determine, to a certain extent, the 

 form, size, character of surface, density, and temperature of 

 objects. We also have a general appreciation of heat and 

 cold ; a sense of resistance, which gives an idea of weight ; 

 and, finally, there are nerves of peculiar properties, termi- 



