20 POWDERED VEGETABLE DRUGS 



sabina has the terebinthine odor characteristic of conifers; upon thor- 

 oughly crushing there is liberated a peculiar and very disagreeable 

 odor. The same is true of worm seed (Santonica) and some other 

 drugs. In consideration of these facts it is advisable to test the odor 

 of the drug before it is crushed or powdered as well as afterward. The 

 odor of powdered drugs weakens very rapidly. The great surface 

 area exposed permits the volatile odoriferous substances to escape 

 very quickly. Very fine comparatively fresh powders of drugs which 

 have well marked odors in the crude state, have only a faint or barely 

 appreciable odor. In the case of coarse and medium powders the 

 odor may readily be accentuated by crushing a pinch of the powder 

 in the palm of the hand or in a small mortar, as already indicated. 



Since the olfactory apparatus is easily fatigued, it is not advisable 

 to test the odor of many drugs in rapid succession. Thoroughly 

 testing from four to eight drugs in the course of one hour will be suffi- 

 cient. The intervals should be long enough to enable the olfactory 

 nerves to recover entirely from each functional depression. 



IV. TASTE AND STANDARDS OF TASTE 



A substance to be tasted must be in solution and must come in 

 contact with the gustatory nerve endings. We are capable of recog- 

 nizing four basic tastes, namely sweet, acid, salt and bitter. The 

 nerve endings which give rise to these different tastes differ structurally 

 and occupy different positions in tongue and oral cavity. Bitter sub- 

 stances produce the most marked effect when placed on the base of 

 the tongue; acids when placed at the lateral edges of the tongue. Any 

 part of the tongue will, however, appreciate any sapid substance. The 

 intensity of the taste is proportional to the strength of the solution and 

 to the gustatory surface acted upon. The sensation requires some 

 time to develop and endures as long as any of the sapid substance 

 is present. Various stimuli will cause sensations of so-called taste, as 

 electrical currents and contact stimuli. Temperature greatly modifies 

 this sense. Very hot or very cold substances cannot be tasted; a 

 temperature of about 40C. is the most favorable. Pungent 

 substances, as pepper, alcohol, etc., greatly obscure any gustatory 

 sensations. 



The gustatory nerves are not quickly fatigued, nor is their sen- 

 sitiveness readily impaired or obscured. It is difficult to cover one 

 taste by another, as is well known by those who are in search for 

 vehicles or menstrua for disguising the taste of disagreeable medicines. 

 Quinine is persistently bitter, no matter what is added to it. Salt is 

 appreciated as long and as often as it may be applied to the tongue. 



