OP ORGANIZED BEINGS. 419 



sion of the papillae of the retina, the substance c oh 

 is a mere congeries of nervous terminations,' This cir- 

 cumstance confirms a former remark, that the immediate 

 organs of sensation were more copiously supplied with 

 nervous papiihe than those parts whose uses require no- 

 such exquisite sensibility ; for a distinction in this respect 

 is observable even among the sensitive organs themselves. 

 The eye is furnished with more of these papillce than 

 any other organ, and this would seem a necessary provi- 

 sion when we consider the minuteness of the particles 

 of light, the impressions of which that organ is fitted 

 to receive. 



' The pleasure or pain produced by the sense of touch, 

 depends chiefly on the friction or number of impulses 

 made upon the papillae. Embrace any agreeable body 

 with your hand, and allow it to remain perfectly at rest, 

 and you will find the pleasure not half so exquisite as 

 when the hand is moved backwards and forwards upon 

 its surface. Apply the hand to a piece of velvet, and it 

 is merely agreeable ; but rest it repeatedly on the surface 

 of the cloth, and the pleasant feeling will be augmented 

 in proportion to the number of impulses on the papillae. 

 When a man is hungry, the sight or idea of palatable 

 food raises the whore papillae of his tongue and stomach. 

 From this circumstance he is highly regaled by eating.' 

 But if he eats the same species of food when his stomach 

 is in a less fit state to receive it, the papillae remain in a 

 flaccid state, and the pleasure is lessened. By the sense 

 of touch we are enabled to ascertain some of the most 

 important, properties of bodies, such as their softness or 

 hardness, their rough or smooth state, their figure and 

 their size ; and it is less deceptive than either of the 

 other senses, because in order to effect it bodies must 

 come in contact with the organ or organs which perform 

 it, whereas in the other senses some intermediate sub- 

 stance may serve to modify or alter the impressions, and 

 thus mislead the judgment. 



The senses of tasting and smelling are more nearly 

 assimilated to the sense of feeling than those of seeing 

 and hearing ; for bodies must come in contact with the 

 papillae of the tongue or palate in order that we ma,j 



