X.] SENSATION AND THE SENSIFEROUS ORGANS. 265 



which renders its possessor proof alike against the 

 poison of superstition and the counter -poison of 

 nihilism ; by showing that the affirmations of the 

 former and the denials of the latter alike deal with 

 matters about which, for lack of evidence, nothing 

 can be either affirmed or denied. 



I have dwelt at length upon the nature and origin 

 of our sensations of smell, on account of the compara- 

 tive freedom of the olfactory sense from the compli- 

 cations which are met with in most of the other 

 senses. 



Sensations of taste, however, are generated in 

 almost as simple a fashion as those of smell. In this 

 case, the sense organ is the epithelium which covers 

 the tongue and the palate : and which sometimes, 

 becoming modified, gives rise to peculiar organs 

 termed " gustatory bulbs," in which the epithelial cells 

 elongate and assume a somewhat rod-like form. Nerve 

 fibres connect the sensory organ with the sensorium, 

 and tastes or flavours are states of consciousness 

 caused by the change of molecular state of the latter. 

 In the case of the sense of touch there is often no 

 sense organ distinct from the general epidermis. But 

 many fishes and amphibia exhibit local modifications 

 of the epidermic cells which are sometimes extra- 

 ordinarily like the gustatory bulbs ; more commonly, 

 both in lower and higher animals, the effect of the 

 contact of external bodies is intensified by the develop- 

 ment of hair-like filaments, or of true hairs, the bases 

 of which are in immediate relation with the ends of 



