1826 Journal of Applied Microscopy 



the edges of the disk to make a tight seal and prevent the entrance of air. The 

 pyrogallic acid soon absorbs the oxygen in the Petri dish, and the anaerobic or- 

 ganisms grow readily, and can be easily studied under a microscope. The 

 author also describes a special form of tube for cultivating anaerobic bacteria. 



H. w. c. 



Biot. A New Method of Intensive Color- The most satisfactory methods of stain- 

 ation of the Bacillus of Koch. Report read ing the bacillus of Koch are those of 

 atthe third session of the Association of Anat- t^, ,. , i r r?- i i ^i 



omists, Lyons, 1901. Ehrlich and of Ziehl; even these pre- 



sent difficulties which, however, the 

 author has at last succeeded in overcoming. In Ehrlich's method the different 

 solutions used are made with difficulty ; they require a long time for their prep- 

 aration, they cannot be procured easily and they do not keep. Ziehl's method 

 is very good, and very rapid, but has the slight drawback of giving the bacilli a 

 more or less decided red tint, and of being hard to manage because the manipu- 

 lator must know how to arrest the process of decoloration at precisely the right 

 moment. This moment, in itself, is difficult to determine, because the bacilli 

 which may already have become decolorized, are no longer visible. 



The method suggested by the author, being certain and expeditious, and 

 eliminating all possibility of error, will be of great value to practitioners. It is 

 as follows : 



Prepare the specimens in the usual way — that is, crush a minute fragment of 

 the substance to be studied between two cover-glasses, which should be sepa- 

 rated almost immediately. Allow them to dry, heat them (in order to insure the 

 coagulation of albuminoid material) by passing them three times through the 

 flame of a Bunsen burner or an alcohol lamp. Into a small porcelain capsule 

 pour 5 to 6 c. c. of water slightly carbolated (2 to o parts per 1000), add to it 8 

 to 10 drops of a saturated alcoholic solution of fuchsin, warm gently until the 

 first bubbles appear, plunge the cover-glass for an instant into a 20 per cent, 

 solution of nitric acid, dip it slowly into the alcohol until the decoloration is as 

 complete as possible (methylated alcohol may be used), wash, and then immerse 

 in a watch-glass containing 2 to 3 c. c. of a 40 per cent, commercial solution of 

 formic aldehyde. The stain of the bacilli will be more or less dark, depending 

 upon the concentration of the aldehyde and the length of time the cover-glass is 

 immersed in it. Two to four minutes is usually sufficient. 



The decoloration should be pushed as far as possible in order that, 

 during the immersion in the aldehyde, the cellular elements which constitute the 

 background may not regain their stain. Afterward wash in pure water, and ex- 

 amine in a drop of water. If the stain is not deep enough, immerse the cover- 

 glass again in the aldehyde for a longer or shorter time. After washing with 

 water, the specimen may be dried and mounted in Canada balsam. The bacilli 

 can be seen in a deep stain which appears to be black, but which is in reality a 

 blackish violet. It is not necessary to counter-stain the background in order to 

 differentiate the bacilli from the other elements. A. Girauld. 



Translated by Eleanor L. Lattimore. 



