262 THE AMERICAN MONTHLY [November, 



slit, W, is cut in the side of the adapter C to allow of the neces- 

 sary motion to the handle D. The amount of this motion is gov- 

 erned by the length of the slit. 



Fig. 3 is a top sectional view, as indicated by the dotted lines 

 X Z in fig. 2. The letters in figures 3 and 3 refer to the same 

 parts. It will be seen in fig. 3 that the slit for the rotation of 

 the mica film allows iSo degrees of motion, which is equal in its 

 optical effects to an entire revolution. In selecting mica films great 

 care must be taken to use only those which are free from bubbles, 

 lines, and other optical defects, and are perfectly, clear, and the 

 richest effects are obtained when used in connection with a red 

 and green selenite film placed in its position over the polarizing 

 prism, and the mica plate so placed in its plane of rotation to the 

 polariscope that it gives a deep, rich violet color to the field of the 

 microscope. This will be the case if the proper thickness of mica 

 film has been selected. 



As before mentioned, it will be noticed that the mica film is 

 placed between the analyzer and the object upon the stage, and 

 in this position it will be found to give new and beautiful effects, 

 in many cases giving great boldness to delicate structure. 



The Practical Use of the Microscope in Pliarniacy.* 



By ALFRED H. DOHME,^ Ph. D. 



Nearly every graduate in pharmacy who has taken his degree 

 during the course of the last tw^enty years has become acquainted 

 w-ith the theories underlying the use of the microscope, and also 

 the results that may be achieved by its use in the hands of a mi- 

 croscopist. I venture to assert, however, that but few of this 

 large number have ever done much practical w'ork with this sub- 

 tle and valuable instrument, and still fewer have ever made any 

 practical use of the same in their profession. 



Medical men have used it more generally for some time past, 

 and since the recent interesting observations and discoveries of 

 our celebrated bacteriologists and histologists all over the scien- 

 tific world, its use is becoming more general every day, so that 

 the time is not distant when every graduate in medicine will be 

 compelled to be skilled in its use and to use it for diagnostical as 

 well as research work. Pharmacy is keeping pace with her sis- 

 ter sciences of bacteriology, histology, and chemistry.. and in this 

 particular branch she must not fall behind, for her advances in 

 the decades to come will be along the line of microscopical work, 

 combined, to be sure, with chemical work. Particularly in 

 these davs of close competition in all lines of trade, consequent 

 upon which is the adulteration of the products, natural as well as 

 manufactured, is it incumbent upon every pharmacist to be able 

 to detect the false from the true and the adulterant from the adul- 



* Read before the American Pharmaceutical Association, 1892. 



