446 ANNUAL REPORT SIMITHSONIAN INSTITUTION, 1937 



ards for those substances which are admitted. There is need for 

 thorough knowledge of the botanical characteristics of drugs and the 

 setting up of standards for these. Here the microscope is an important 

 scientific instrument in determining the quality and identity of the 

 drug. The plant structure or some specific microchemical test giving 

 distinctive colors or crystals or reactions enter into the preparation 

 of standards. 



In a number of instances where there are specific crystalline prin- 

 ciples of the alkaloidal type, as in cinchona, which contains quinine 

 and related alkaloids, as in nux vomica with its active principle 

 strychnine, or in opium with morphine, codeine, etc., as the active 

 agents, or in drugs of a similar character, tests are required by which 

 these highly potent crystalline principles arc extracted and their quan- 

 tity actually weighed or otherwise estimated. This method of pro- 

 cedure is known as a "proximate assay," 



In other drugs the activities are represented by substances which 

 cannot be extracted or weighed but the potency must be measured 

 by their action on animals. For instance, the very important drug 

 ergot has within it various alkaloidal substances which produce dis- 

 tinctive physiologic effects upon living tissue. One test, which has 

 been widely used, depends upon the effect of one of these principles 

 upon the comb of a rooster. The change is due to the contraction of 

 the capillaries or small blood vessels in the comb, causing it to become 

 darker in color, and the degree to which this is affected by known 

 quantities of the drug, in comparison with a standard, is one means 

 for determining its potency. Other biological tests, registering the 

 actual effect of a drug upon an animal or one of its organs, must 

 be used for the standardization of digitalis, aconite, pituitary, 

 epinephrine and similar important and powerful drugs. In other 

 cases, the absence of toxicity in a chemical such as arsphenaminc is 

 determined by injecting the substance into mice to assure freedom 

 from dangerously toxic substances which might otherwise prove 

 fatal to a patient. Other medicinal agents, chemical in nature, are 

 standardized by many ingenious tests. 



Frequently a reagent will bring about a distinctive color or a 

 precipitation or cause some other reaction wliich indicates identity. 

 Then the substance is usually tested for foreign substances or adul- 

 terants and again distinctive reactions result when standard reagents 

 are added, and these indicate the absence or the presence of such for- 

 eign substances. 



In the manufacturing of chemicals there is always danger of 

 introducing foreign materials. These may come from the apparatus 

 used in manufacture, or from the chemical substances entering the 

 process, or from other causes. So there are usually tests to exclude 



