SMELL 



361 



effects also are observed here as in the other senses. Some drugs abolish 

 the senses of taste in various ways; thus, for example, cocaine abolishes 

 the bitter taste first. 



FIG. 213 



SMELL. 



This sense, as already suggested, is far less important in the conduct 

 of life in man than it is in many of the lower animals. Dogs, for 

 instance, apparently obtain more information through their sense of 

 smell than even by vision. In man it serves, much as does taste, to 

 furnish both pleasure and protection and to incite to fulness of function. 

 In this, respiration is chiefly served, for in the flowery fields of summer or 

 the spruce forests it impels the organism to inhale deeply the pure air, 

 while in places where the air would harm instead of benefit, it causes us 

 to reduce as far as possible its intake 

 and to escape from it at once. More- 

 over, when the air is sweet it incites 

 respiration through the nose, its proper 

 organ, rather than by the mouth. As a 

 further protection it warns us away from 

 putrid food unfit to be eaten and from 

 water too full of vegetable matter to be 

 proper drink. Its sexual relation, very 

 important in most of the brutes, is nearly 

 obsolete in civilized man except in the 

 feminine use of perfumes. To a less 

 extent than taste, smell serves as the 

 sense by which go inward the impulses 

 which reflexly start the secretion of the 

 digestive juices. Thus, the odor of roast- 

 ing meat makes a hungry man's mouth 

 "water" and, as we have already seen, his 

 stomach as well. Helen Kellar empha- 

 sizes how useful the sense of smell is to 

 her, each acquaintance, for example, 

 having a unique odor appreciable at 

 some distance. 



The Olfactory Apparatus is simple so far 

 as mechanism is concerned, for it consists 

 wholly of peculiar cells embedded in 

 mucous membrane, of neurones, and of 

 centers in the brain. 



THE OLFACTORY CELLS are the cell-bodies of non-medullated neur- 

 axes whose teleodendrites are in the olfactory bulbs. They are fusiform 

 cells each with a round nucleus and a large nucleolus in the thickest part 

 of the spindle. Toward the free mucous surface the cells terminate in 

 blunt cones upon each of which stand seven or eight bristle-like filaments, 



Olfactory cells from the Schneiderian 

 membrane: 1, from that of a dog; 2, 

 from man; b, the olfactory cells; a, 

 supporting cells. The hair-like fila- 

 ments, e, on the upper ends of the 

 cells extend outward on the moist 

 surface of the mucosa. (Schultze.) 



