EXAMINATION OF VEGETABLE POWDERS 13 



the users of tobacco and the atmosphere about them. Consumers of 

 alcoholic drinks are not aware of their alcoholic breath. Those who eat 

 onions and garlic are not conscious of the sulphurous odor which is 

 so annoying to others. Those affected with ozcena or bad breath, 

 due to nasal catarrh, a disordered stomach or bad teeth, are not con- 

 scious of the odor. 



The condition of the olfactory organs greatly modifies the apprecia- 

 tion of odors. If the nasal passages are more or less occluded through 

 catarrhal inflammations, pathological growths as polypoids, etc., the 

 sense of smell may be very much reduced or practically zero. 

 Those affected with chronic nasal catarrh have a weak and otherwise 

 abnormal sense of smell. The sense of smell in different persons differs, 

 not only by inheritance, but also by education. Savage races and 

 many of the higher herbivora and carnivora have an exceedingly acute 

 sense of smell for certain odors, while for other odors this sense is quite 

 dull. Man is capable of educating this sense to a very high degree, 

 as in " wine-tasters," and tea examiners, who are capable of detecting 

 differences in aroma which wholly escape the inexperienced. 



In order that the sense of smell may be fairly delicate, the nasal 

 passages should be unobstructed, the nasal membrane entirely free 

 from inflammation and other abnormal conditions. The membrane 

 should be quite moist with the natural secretion of the mucus cells, 

 rather than comparatively dry. The nasal passages are also well 

 supplied with nerve endings of common sensation, which will explain 

 why many tactile sensations are mistaken for odors, as, for example, 

 the so-called pungent odors. In contradistinction to the other senses, 

 electrical, thermal and mechanical stimuli do not cause sensations of 

 odor. 



The intensity of the odor is directly proportional to the concentra- 

 tion and volume of the odoriferous gas and the rate with which it 

 passes through the nostrils. The olfactory apparatus is extremely 

 sensitive when in a perfectly normal state. According to some authori- 

 ties, the odor of mercaptan is still quite marked when diluted 300,000,- 

 000 times, and becomes inappreciable only when diluted 500,000,000 

 times. The odor of chlorphenol is still noticeable when diluted 

 1,000,000,000 times. Certain drugs and chemicals will modify the 

 sense of smell. Anodynes and soporifics will reduce it in activity 

 while strychnin and some other substances will increase its activity, 



As regards the estimates of the quality of odors, there is even<greater 

 uncertainty than there is concerning the quantity. In a general way 

 odors are designated as agreeable or pleasant, indifferent, and disagree- 

 able; but it becomes evident that such a classification is very unsatis- 



