84 The Microscope. • 



It 



tained in a watch glass, (an individual butter dish is cheap and con- 

 venient,) and allow it to remain at least twelve hours. After staining 

 wash the cover glass in pure water and decolorize in a 33 per cent, 

 solution of nitric acid until the sputum appears nearly colorless. A 

 second washing in water follows, and if the red reappears, but rather 

 pale, the process has been carried far enough. If, however, the 

 specimen is entirely colorless after the second washing, it is an indi- 

 cation that it has been too long in the nitric acid, and on examina- 

 tion, the bacilli will be found only faintly visible, if at all. Just 

 here the greater number of failures occur, and only practice can de- 

 termine how far to carry the decolorizing. It is, however, far 

 better to decolorize too little than too much. 



When time is important, heat the fluid to 50^C., and allow the 

 cover glasses to remain in an hour. They can be still more rapidly 

 stained by making the staining fluid a little stronger and the prepa- 

 rations heated to about GO'^C. Fair results can be had in twenty to 

 thirty minutes. In all cases of quick staining the nitric acid solu- 

 tion should be much weaker, from 5 per cent, to 15 per cent. A 

 double stain is not necessary, but if one is desired, float the cover 

 glass on a saturated aqueous solution of methyl blue for from three 

 to five minutes and then wash. For mounting, use glycerine, as it 

 can be washed oft* if it is desired to permanently mount the speci- 

 mens in balsam. The author also recommends a convenient method 

 of preserving and at the same time staining sputum. The solution 

 can be given to the patient and the sputum first coughed up in the 

 morning may be presei-ved. Formula of solution : 



Aniline oil solution, as above, "ij; fuchsine stain, M. xx; car- 

 bolic acid, ten per cent, solution, M. v. 



This solution should be prepared fresh. The sputum should be 

 left in the stain twenty-four hours and if not then sufiiciently stained 

 resort may be had to the ordinary method. The specimen is to be 

 decolorized and mounted in the usual manner. 



Karyokinesis.— In the study of karyokinesis in the arthropods. 

 Professor J. B. Carnoy obtained the best results with the two fol- 

 lowing mixtures: (1). Chromic acid (2 p. c. or more), 45 parts; 

 Osmic acid (2 p. c.) 16 parts; Glacial acetic acid, 3 parts. (2j. Cor- 

 rosive sublimate. Glacial acetic acid (1 p. c). The object (testes) is left 

 from six to ten minutes in one of these mixtures; then washed in 

 distilled water and further hardened in alcohol.— .Imer^can 

 Naturalist. 



