a stimulus alters with the duration of an inspiration as well as with the manipulation of the instrument, the subject must make more than one inspiration to determine a limen, unless the judgment is very easy. It is probable that the first part of the inspiration, before the smell "blossoms out," gives the best criterion of the intensity of a stimulus. We would suggest that cumulative stimulation of smell would be a profitable subject of investigation. In an effort to smell with the standard olfactometer, C., D., K., P., Rob., Rog., Sh. and T. all tipped the head to the left if using the left nostril, and to the right if using the right, pointed the outward end of the inhaling-tube in the same direction as the head was tipped, and slanted the screen in the opposite direction. This odd uniformity is perhaps explicable. On entering the nose the air ordinarily streams a little toward the septum and the opposite directions in which the subject slanted his head and the screen tended on each side to throw the opening of the nose-piece into an acute angle with the septum, while the turn given to the instrument in the horizontal plane threw the opening a little toward the front of the nose. On the other hand, Se. exactly reversed these directions on each side, and so did Be., except that he turned the tube to point in the same direction as the screen was slanted, so throwing its inner opening towards the back of the nose. Bi. slanted both head and screen to the right when using the right nostril, and to the left when using the left. This was probably a mere matter of attention to one nostril or the other. She was not consistent in the pointing of the tube. N. turned everything to the right. Unfortunately, no written notes were taken of the hand used, but it was usually the right, the hand farther from the experimenter. All the subjects tended to tilt the hand forward and the screen backward, probably in their desire to get "nearer" the stimulus. Almost all, unbidden, closed their eyes. sensa T. once mentioned verbal associations as an aid in memorizing the stimulus. This expedient was not common. Be. wrinkled his forehead and nose in a marked degree, and once noted a tendency to judge in terms of strain, especially about the eyes. Some substances were pungent to a disturbing extent to every one, but C. and D. complained much of " pain" from odors which no one else thought pungent. D. explicitly distinguished the sensation from pressure. He thought coumarine both pungent and "sour." Both C. and D. said that they received simply sensations of pressure from some stimuli. With D. sensations of smell merged in tions of pressure as the organ became exhausted. C. said that when she tried to smell the black rubber with the left nostril she merely felt as if she were "breathing a feather," or as if the inside of her nose were "pressed with a soft wad." Yet the judgments made with this nostril agreed pretty well with those made with the other. Be. occasionally spoke of sensations of pressure or pain from the stimuli. Most of the subjects expressly denied temperature-associations. Be., however, said that tolu and heliotropine were cold; M. that cocoa-butter was cold; Rob. that vanilline was cold; and N. that white tallow and musk-root were warm, and camphor cold, and that every smell grew warmer as it grew stronger. He thought of heliotrope as "warm, dark and deep," in contrast with ylang ylang, which was " light and fluffy." The comparative sensitivity of the subjects may be judged from the following Table: TABLE I. A TABLE OF STIMULUS-LIMINA. Part I. Stimulus-Limina Arranged to Show Individual Variations. Part 2. TABLE I.-Continued. Stimulus-Limina Arranged to Show Variations Due to THERMOMETER SUBJECT. SUBSTANCE. NOSTRIL. Value of rλ in cm. READING. All the values of rλ given in this Table are averages of several determinations taken on the same day. Those enclosed in parentheses were found when the subjects had had little or no experience with the substances in question. Those not so enclosed were found after the respective substances had been used by the several subjects in difference determinations. In the first part of the Table, the limen given is in every case the last limen found for the subject and substance, and all the last limina found are given. The second part of the Table simply contains results selected by way of illustration, but all the limina found for the subject with the substance in question are included. In Part 1, all the substances but the last four are taken in order from a Table in which Zwaardemaker arranges various materials for solid odorous cylinders in the order of their intensity. The limina in the column headed Z are those given by him in another Table as normal at a temperature of 15° C., or 59° F.2 The temperatures at which our records were taken lay for the most part between 60° and 70° F. Our limina ought, therefore, to be lower than his, instead of higher. We cannot satisfactorily explain the difference between our results and his in the matter of stimulus-limina. That the limina of Americans should be higher than those of Dutchmen is not indeed surprising, but the entire change in the rank of the substances is. According to Dr. Reuter, as cited by Zwaardemaker, the gum ammoniac and gutta-percha cylinder is forty times as strong as the vulcan ized rubber, and the musk-root is five times stronger than the former. The tallow, Zwaardemaker says, is stronger still. We regret that we could not find stimulus-limina oftener. The washing of the tube consumed so much time that this was impossible. We feel that the results embodied in Table I are the most unsatisfactory part of our work. Yet if allowances be made for exhaustion in some of the results of C. and Sh., and for expectation gradually controlled by practice in the cases of Bi., M. and Rog., the Table will serve its purpose.1 We have not space to give our temperature records in full. They varied so irregularly that the arithmetical mean by no means represents the most common reading. As the steam had to be kept shut off when we were not in the laboratory, the exact regulation of the temperature involved serious practical difficulties, and for most of our work it was a matter of minor importance, for in difference-determinations variations of temperature and moisture affect the standardstimulus and the stimulus of comparison equally, and may, therefore, be disregarded. Indeed, our barometer-records, though carefully kept, proved to be wholly a work of supererogation, for in the case of the very few substances (glycerine soap, coumarine, heliotropine, vanilline, and allyl sulphide) which were somewhat soluble in water and yet not in aqueous solution, we did not succeed in finding stimulus-limina on different days.2 Practice lowered the stimulus-limina in a conspicuous manner, but the effect of variations in temperature can only occasionally be traced in the complete results. Part 2 of Table I illustrates this fact with fairness. It only remains to say that Be., C., K., N., Se. and T. worked twice a week for at least part of the year and the others once. Section 2. Results Obtained by the Method of Just Since in the nature of the case numerical proof of the applicability of Weber's law to a given sense department cannot be thrown into the form of averages, and since we have not space for the great mass of figures which we have at hand, we must offer first samples and then summaries of our evidence, and content ourselves with them. Tables II and III are the samples, and Tables IV, V and VI are summaries from different points of view. TableI V constitutes the most decisive proof of the validity of the law. Tables V and VI are intended to confirm the conclusion to be drawn from Table IV, and to show the probable value of Ar. In Tables r III, IV, V and VI, every value given or enumerated is an average of the results of one day's work with one subject, nostril, substance and standard. All the work done with this method, however unsatisfactory, is represented in Tables V and VI. 1 The writer's own limina are lower than those of any of the subjects. Abnormal keenness of smell has persisted from childhood, in spite of the usual share of "colds." 2 For the effect of atmospheric moisture in Zwaardemaker's method, see Chapter I, Section 2. TABLE II. CONSECUTIVE RESULTS OF ONE SUBJECT, T. 22 22 12 22 3,2 13 6(1) 6(1)| 34 7(1) 3(2) 5 A [6] Exhaustion. 3 Exhaustion. 9 10(-) 1(2) 52 8(1) 14(0) II 8(2) 8(1) 8 8(3) 8(3) 8 12 10(1) 8(1) 9 9(2) 7(1) 8 A 56 14(2) 7(4) 10% 5 General fatigue. 2 [3] 3 [3] 233AA52 |