12 POWDERED VEGETABLE DRUGS 



the finger is brought in contact with an object. Cold reduces sensi- 

 tiveness very rapidly; washing in warm water restores the normal 

 activity promptly. 



Moisture greatly modifies the consistency or feel of powders. For 

 instance, a powder which appears quite crisp or brittle when dry may 

 become quite soft and somewhat fibrous in moist weather, indicating 

 the presence of bast or perhaps elongated parenchyma cells (many 

 barks) . 



Tactile sensations usually designated as tastes and odors will be 

 explained later. We would advise students to depend largely upon 

 the tactile sense of the hand and fingers, though lips, tongue and mouth 

 are more sensitive. Frequent and promiscuous tasting and chewing 

 of drugs is pernicious for several reasons. 



III. ODOR AND ODOR STANDARDS 



The olfactory apparatus is undoubtedly the least reliable of all the 

 sense organs. There is no standard of odors, nor do we have any 

 means of measuring odors. A number of individuals may smell the 

 same odor, but they have no means of comparing either the quality 

 or the quantity of the odor. This being the case, it naturally follows 

 that there is no reliable odor nomenclature. Odors are variously clas- 

 sified as agreeable or pleasant, indifferent, strong, faint, fragrant, 

 aromatic, heavy, acid, pungent, sweet, etc., words which are variable 

 in interpretation and in application. An odor is said to be strong or 

 faint according to individual judgment. An odor may be " overpower- 

 ing" to one person, while another will pronounce it moderately strong. 



A substance capable of stimulating the olfactory apparatus to 

 functional activity must be in a gaseous state. The odoriferous gas or 

 vapor must enter the anterior nares in a large and continuous cur- 

 rent. If the nostrils are held shut, though the passages are filled 

 with the odoriferous gas, no odor can be detected. Filling the nostrils 

 with liquids holding odoriferous gases in solution will not produce any 

 effect upon the olfactory nerves. It is also interesting to note that 

 odors entering the nostrils by way of the posterior nares cannot be 

 smelled. 



The olfactory nerves become fatigued very quickly, as is evi- 

 denced by the readiness with which one becomes " accustomed" 

 to an odor. Tenants of ill-ventilated rooms, in which the stench 

 is often overpowering, do not complain of any bad odor. Those ad- 

 dicted to the use of tobacco are unconscious of the strong odor which 

 not only permeates the entire clothing, but also the entire system of 



