THE SENSE OF TOUCH. 7 



Even among the most liigbly specialized organs of 

 sense, it is impossible not to be struck by the similarity 

 between the cones in the retina (Fig. 79) and certain 

 organs in the antennas of insects (Fig. 42) which are 

 generally considered as olfactory. It does not follow 

 that an organ >vitli a nerve, a lenticular body, and 

 pigment, should necessarily be an eye. Nor, on 

 the other hand, is there anything in the structure 

 of the organs, for instance, of smell or taste which 

 throws any light on the perceptions we receive from 

 them. That there should be separate nerve-fibrils in 

 our own skin, not only for the sensations of temperature 

 and of touch, but, as appears from the researches of 

 Blix and Goldschneider, even of heat and of cold, we 

 had not anticipated a priori; and it would be difficult 

 to prove in any animal but ourselves. 



The Sense of Touch. 



I commence with the sense of touch, as being the 

 one which is most generally distributed, and from 

 which the others appear to have been in some cases 

 developed. The senses are not, indeed, as already 

 mentioned, always to be easily distinguished from one 

 another ; and it would seem that the same nerve may 

 be capable of carrying different sensations according to 

 the structure of the end organs. 



The sensibility of our skin appears to be mainly due 

 to a plexus of fine nerve-fibres, which end in free termi- 

 nations between the cells of the skin (rete mucosum). 

 There are also in some parts of the skin two sets of 

 minute corpuscles, which are called after their discoverers, 

 the first Vaterian, or more commonly Pacinian, cor- 

 puscles; the second, Meissner's or Wagner's corpuscles. 



