THE MICROSCOPE. 201 



[Prepared by Geo. A. Hendricks, M. D., Assis'ant Demonstrator of Anatomy, Univeriity of 



Michigan.] 



New Methods for the Detection of the Tubercle Bacil- 

 lus. — Ehrlich's method as demonstrated by G. A. Heron, M. D.,. 

 before the annual meeting of the British Medical Association, may 

 briefly be described in the following manner: Sputum is spread ia 

 thin layers upon cover glasses, and allowed to dry; then exposed 

 for about twenty minutes to a temperature of 212'' Fahr., or passed 

 quickly three or four times through the flame of a gas jet or of a 

 spirit lamp. They are now ready to be stained with any one of the 

 aniline series of dyes. Fnschine and gentian violet are two of those 

 which Ehrlich has used. In this process these colors are handled 

 in precisely similar ways. A description of one will suffice. Make 

 a saturate alcoholic solution of fuschine, also prepare a saturated 

 watery solution of aniline prepared as follows: Five cubic centi- 

 metres of aniline are added to one hundred cubic centimetres of 

 distilled water. Shake frequently for twenty minutes, then pass 

 through a moistened filter. The filtrate contains from three to four 

 per cent, of aniline, and should be as clear as good drinking water. 

 To thirty cubic centimetres of the filtrate are added thirty drops of 

 the alcoholic solution of fuschine. If a glistening metallic film does- 

 not appear upon the surface of the mixture, continue to add more of 

 the fuschine solution until the film is clearly marked. 



The cover glasses prepared in the way already described are 

 allowed to float for thirty minutes, sputum downwards, upon the 

 surface of a suflticient quantity of the straining fluid, poured into a 

 suitable vessel. When removed the sputum will be strained to a 

 deep red color. The greater part of this deep red color must be 

 removed by washing the cover glasses in a mixture of one part of 

 the acidum nitricum (not dilutum), of the British Pharmacopoeia^ 

 and two parts of distilled water. Here the beginner may have some 

 difficulty, for he is apt to leave too much of the red dye upon the 

 sputum. After the washing with nitric acid there should be, at 

 most, a slight white-pink tinge, visible to the naked eye, in the 

 sputum. The acid is washed out by dipping the cover glass in dis- 

 tilled water. If bacilli of tubercle are present in the specimen, they 

 will be seen microscopically, as red rods, here and there, and per- 

 haps in clusters, upon a colorless or whitish-pink ground. When 



