1892.] THE MICKOSCOPE. 151 



idea of what can be done is shown by the work that the Depart- 

 ment of Agriculture of the Government is doing in the examina- 

 tion of spices. See " Bulletin No. 13 " of this Department. 



Many of the histological elements of plants are such that they 

 are readily recognized, even in the mutilated condition found in 

 powders. It is often possible to identify cells from pith and other 

 characteristic tissues, like the bast in cinchona, the stone of cin- 

 namon, and the pitted ducts of red cedar. I remember an instance 

 where a sample of powdered red pepper was simpl}^ fine red cedar 

 sawdust flavored with the oleroesin of pepper. A glance at the 

 mixture under the microscope revealed its true nature. In coarse 

 powders it is sometimes possible to recognize the stomata of 

 leaves. 



d. Pharmacognacy, or the recognition of drugs, is studied by 

 aid of a system based upon the physical characteristic of the sub- 

 stances. As an example, we study the structure and characteristics 

 of a leaf, which is one of the subdivisions of that srreat class of 

 drugs derived from the vegetable kingdom. Leaves are again 

 subdivided into two kinds, the herbaceous and coriaceous. These 

 two classes are readily distinguished from each other bv an exami- 

 nation without the aid of the microscope. However, the case 

 differs when we come to the study of several other subdivisions 

 of vegetable drugs. For instance, we take the roots, which is a 

 subdivision corresponding to the leaves. The roots are divided 

 into two similar subdivisions, known as the mono-cotyledonous 

 and the di-cotyledonous. It is by means of examining a trans- 

 verse section of these roots under the microscope that the phar- 

 macist determines to which subdivision thev belonsf. The di- 

 cotyledonous are again subdivided into woody, with thick bark ; 

 woody, with thin bark and fleshy roots. As is readily understood, 

 this classification is based solely upon characteristics revealed by 

 the microscope. To continue with the subdivision one step fur- 

 ther, we have the woody roots with thick bark, divided into those 

 with oil, resin, or latex ducts and those without oil, resin, or latex 

 ducts. 



The advantage of such a system of classification is an inter- 

 esting subject, but does not directly concern us as microscopists. 

 Its consideration usually occupies an entire lecture in the College 

 of Pharmacy. 



e. The use of the microscope in microchemistry is not advanced 

 as far in pharmacy as the use of the instrument in vegetable his- 

 tology. The principal reason for this is owing to the difiiculty 

 of studying crystallography. A few of the more common salts 

 like the cinchona alkaloids have been studied and their micro- 

 chemical appearance are figured in the dispensatories. I have 

 no doubt that microchemistry applied to pharmacy will be greatly 

 advanced by the active pharmacist of the future. 



