SENSE OF SMELL. 



743 



increased when other senses are deficient. Thus, in the well-known case 

 of James Mitchell, who was blind, deaf and dumb, from his birth, it was 

 the principal means of distinguishing persons, and enabled him at once 

 to perceive the entrance of a stranger. It is recorded that a blind gentle- 

 man, who had an antipathy to cats, was possessed of a sensibility so acute in 



FIG. 259. 



Distribution of the Olfactory Nerve on the Septum Nasi. The nares have been divided by a longi- 

 tudinal section made immediately to the left of the septum, the right nares being preserved entire. 

 1. The frontal sinus. 2. The nasal bone. 3. The crista galli process of the ethmoid bone. 4. The sphe- 

 noidal sinus of the left side. 5. The sella turcica. 6. The basilar process of the sphenoidal and occipital 

 bones. 7. The posterior opening of the right nares. 8. The opening of the Eustachian tube in the upper 

 part of the pharynx. 9. The soft palate, divided through its middle. 10. Cut surface of the hard palate. 

 a. The olfactory peduncle, b. Its three roots of origin, c. Olfactory ganglion, from which the filaments 

 proceed that spread out in the substance of the pituitary membrane, d. The nasal nerve, a branch of 

 the ophthalmic nerve, descending into the left nares from the anterior foramen of the cribriform plate, 

 and dividing into its external and internal branch, e. The naso-palatine nerve, a branch of the spheno- 

 palatine ganglion, distributing twigs to the mucous membrane of the septum nasi in its course to (/) 

 the anterior palatine foramen, where it forms a small gangliform swelling (Cloquet's ganglion) by its 

 union with its fellow of the opposite side. g. Branches of the naso-palatiue nerve to the palate, h. Pos- 

 terior palatine nerves, i, i. The septum nasi. 



this respect, that he perceived the proximity of one that had been accident- 

 ally shut np in a closet adjoining his room. Among Savage tribes, whose 

 senses are more cultivated than those of civilized nations, more direct use 

 being made of the powers of observation, the scent is almost as acute as in the 

 lower Mammalia: thus it is asserted by Humboldt, that the Peruvian In- 

 dians in the middle of the night can distinguish the different races, whether 

 European, American Indian, or Negro ; and the Arabs of the Great Desert 

 are said to be able to distinguish the smell of a fire thirty miles off. The 

 quantity of some odorous bodies which is capable of exciting a distinct per- 

 ception of smell, must in some instances be exceedingly small. A very 

 minute trace of sulphuretted hydrogen is readily recognized, and according 

 to Valentin, one part of bromine in 200,000 of air communicates an un- 

 pleasant odor to the latter, whilst in the case of musk a proportion not 

 greater than one part in 13,000,000 of air is still perceptible. The agree- 

 able or disagreeable character assigned to particular odors, is by no means 

 constant amongst different individuals. Just as many of the lower animals 

 pass their whole lives in the midst of odors that are to Man (in his civilized 

 condition at least) in the highest degree revolting, and will even refuse to 



