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20 and that the drying of this mucus, as in the first stage of rhinitis, impairs the sense of smell. Tortual and Weber had indeed proved that odorous liquids when introduced into the nose “do not smell,” and Weber had also found that the sense is for a time impaired if warm or cold water or sugar and water are poured into the nasal cavities and retained there for a few moments. Aronsohn explained these phenomena by supposing that strong solutions of odorous matter and liquids of foreign temperature if brought in contact with the delicate oliactory membrane must necessarily have a pernicious effect. He found, on the other hand, that very small quantities of odorous substances dissolved in normal saline solutions can be sensed if the mixture, at a temperature of about 40° C., is poured into the nose from the height of about half a meter, Weber used cologne and water in the proportion of 1:11. Aronsohn used oil of cloves, for example, in salt and water in the proportion of 1:500. His olfactometric method consisted simply in determining how weak a solution of an odorous substance could be sensed if injected at the temperature proved empirically to be most favorable for its detection. If Aronsohn's premises are correct, not only is his method direct, but the worst difficulties in the measurement of smell-stimuli are eliminated. In criticism of these premises, however, Zwaardemaker points out (1) that aquatic mammals have organs which resemble the organs of smell in land mammals, but are rudimentary, as if useless underwater ; (2) that the dryness of rhinitis is confined almost exclusively to the Schneiderian membrane and is conjoined with hyperaemia and swelling which obstructs the passage of air; (3) that the cilia of the olfactory cells protrude through the covering of mucus; and (4) that most odorous substances are not at all or are but very slightly sotuble in water. Books on the perfume-industry are filled with the discussion of ethereal oils, of spices, gums, and the like. In a room saturated with perfume or tobacco smoke, a bit of cotton wool will take up the odor, while a glass of water will not. Moreover, as Zwaardemaker believes, it cannot be shown that Aronsohn succeeded in filling the cavity which contains the olfactory membrane so entirely with liquid that all bubbles of air were excluded. It is very difficult to drive all the air out of blind pouches.

In 1893, Dr. N. Savelieff in the laboratory of Morokschowetz constructed an olfactometer on a principle entirely different from Zwaardemaker’s. There were two flasks of glass, each with two corks, Through one cork in each, the two flasks were connected by a glass tube bent twice at right angles. Through the other cork of one was inserted a glass tube which reached to the bottom. Through this tube a mixture of ethereal oil and water was poured. The liquid did not reach the end of the connecting tube. Through the remaining cork of the second flask, which was filled only with air, was inserted a glass-inhaling tube which divided into a nose-piece for each nostril. The odor of the liquid was weakened by successive additions of water, and the intensity of the stimulus was measured through the proportion by weight which the ethereal oil bears to the water. As Zwaardemaker suggests the method of Savelieff has this great disadvantage, that its results do not stand in simple relations to the real stimulus-intensities. The intensity of the stimulus will vary according to the height of the liquid in the first vessel, and according to the