determined in a positive way. These relations, as concerns odors, can have no other basis than a capricious and relative sensibility. They are thus incapable of being reduced to form, a fortiori of being translated into fixed precepts.
To complete these details, it remains to say something of the delusions of the sense of smell; for this sense, like the others, has its aberrations and hallucinations. The delusions of smell are hardly ever isolated; they accompany those of hearing, sight, taste, and touch, and are also less frequent than the latter. Insane people, who are affected by them, complain of being haunted by fetid emanations, or congratulate themselves on inhaling the most delicious perfumes. Lelut mentions the case of a woman, an inmate of la Salpêtrière, who fancied that she constantly perceived a frightful stench proceeding from the decay of bodies she imagined buried in the courts of that institution. Impressions of the kind are usually very annoying. Brierre de Boismont relates the account of a woman affected by disorder of all her senses. Whenever she saw a well-dressed lady passing, she smelt the odor of musk, which was intolerable to her. If it were a man, she was distressingly affected by the smell of tobacco, though she was quite aware that those scents existed only in her imagination. Capellini mentions that a woman, who declared that she could not bear the smell of a rose, was quite ill when one of her friends came in wearing one, though the unlucky flower was only artificial.
Such facts might be multiplied; but, as they are all alike, it is not worth while to mention more of them. The latest observations made in insane asylums, among others, those of M. Prévost, at la Salpêtrière, have shown also that these delusions and perversions of the sense of smell are more common than had hitherto been supposed among such invalids, and that if they usually pass unnoticed, it arises from the fact that nothing spontaneously denotes their existence.
The intensity and delicacy of the sense of smell vary in mankind among different individuals, and particularly among different races of men. While some persons are almost devoid of the sense of smell, others, whose history is related in the annals of science, have displayed a refinement and range in the distinction of odors truly wonderful. Woodward, for instance, mentions a woman who foretold storms several hours before their coming, by the help of the sulphurous odor, due probably to ozone, which she perceived in the atmosphere. The scientific journals of the day relate the account of a young American girl, a deaf-mute, who, by their odor alone, recognized the plants of the fields which she collected. Numerous instances, moreover, prove that in savage races this sense is very greatly more developed than among civilized men. It is a traveler's story, that some tribes of Indians can pursue their enemies and animals of the chase by mere scent.
But it is among the other mammals that we find the sense of
