SCOPE AND PROBLEMS XV 



portions of living plants furnishing the drugs of commerce, but the 

 entire plant. This is necessary, if we would understand the real 

 significance of the characteristics of drugs. Fortunately, also, 

 plants are being studied at close range and under conditions of culti- 

 vation, so that there will be less misapprehension in regard to the 

 authenticity of the materials entering commerce. In former years a 

 number of mistakes have been made in describing drugs which might 

 have been avoided had the identity of the material been first deter- 

 mined and the foundation studies made upon the living plant. 



Histological Pharmacognosy. The development of modern 

 pharmacognosy may be said to date from the initial studies on the 

 inner morphology or the anatomy of plants. All of these studies 

 show that in the cellular structure of plants we find the plant unit. 

 The importance of this discovery will be at once apparent when we 

 recall that very many plants, as well as drugs, may resemble each 

 other very closely when viewed macroscopically, but when we come 

 to examine their cellular structure we find that the nature of the cells 

 and their contents or their arrangement is constant for the most part 

 for the same drug, and vary in different plants or drugs. 



This advance in the study of plants is largely due to Schleiden, 

 who, in 1838, announced that the cell is the fundamental unit in 

 plants and showed that all the different tissues are combinations 

 of cells. Schleiden not only contributed very largely to the knowl- 

 edge of the structure of plants, but was among the first to recognize 

 that drugs of different origin might be determined by their cellular 

 differences. Without having any knowledge, for instance, that the 

 several commercial sarsaparillas were obtained from different species 

 of Smilax, he showed by reason of certain differences in the cells of 

 the hypodermis and endodermis that they must be obtained from 

 different species, which has since been proven to be the case. 



Schleiden early saw that pharmacognosy was to be a distinct 

 science. He designated pharmacognosy as a botanical discipline, 

 indeed he said: "Pharmacognosy is the mother of all scientific 

 discipline." When Schleiden said this he no doubt had in mind 

 the difficulties attending pharmacognostical work and recognized 

 the value of the training required in this study. For the phar- 

 macognocist working upon dried materials must have in mind the 

 relationship between the fragments of the drug he is examining 

 and the growing plant. 



Adulteration in Drugs. By adulteration we mean the deteriora- 

 tion or deficiency in quality of a commercial product, (no matter 

 what this may be due to) , It may be due to a variety of causes such 



