460 APPENDIX 



used, until all the colour has entirely disappeared. Then decolorise in 

 25 per cent, acid solution for a few seconds, wash in water and alcohol 

 and acid alternately, and counter-stain as usual. Honsell recommends 

 acid alcohol (absolute alcohol 97 per cent., HCl 3 per cent.) for ten 

 minutes before counter-staining. With a little practice, the staining of 

 the bacillus of tubercle when present in pus or sputum becomes a simple 

 and accurate method of diagnosis. A small particle of sputum or pus is 

 placed between two clean cover-glasses, and thus pressed between the 

 finger and thumb into a thin film. This is readily dried and stained as 

 above. But washing in alcohol and acid is not a reliable method of 

 differentiation between the tubercle bacillus and other acid-fast organisms. 

 Animal inoculation is the only reliable test. 



Examination of Moulds. — The examination of hyphomyeetes or 

 mould fungi is, for differentiation purposes, best carried out on the Petri 

 dish itself, where the construction of the microscope will admit of this 

 being placed on the stage. 



By the following method there is but little difficulty in recog- 

 nising the various species, and an excellent demonstration is given of 

 the hyphae with interstitial cells, and germinating conidia of the Oidimn 

 lactis, the conidiophore and sclerotium of the Pendllium glaucum, or the 

 ramified mycelium, sporangia, and germinating zygospores of the various 

 species of Mucor, without disturbance of the growth. By means of a 

 finely drawn pipette allow to fall upon the centre of the mould colony a 

 small drop of aqueous solution (1 per cent.) of eosin. It is necessary to 

 exercise a little care in this, or the liquid will at once run off the colony 

 on to the surrounding medium. Place carefully upon the centre of the 

 drop a thin cover-glass, and press in order to obtain close contact. 

 Remove the Petri dish to the stage of the microscope, and examine the 

 margins of the growth with a sixth objective. 



If the construction of the microscope will not allow examination on 

 the Petri dish, or if a permanent specimen is desired, the following 

 method can be recommended : — Detach by means of a pair of fine- 

 pointed forceps a portion of the young growth, holding it by the base, 

 and place it carefully on a slide. Place near it one drop of ammoniated 

 alcohol, and bring this in contact with the specimen by means of a finely 

 pointed needle. The absorption of the alcohol will allow the subsequent 

 penetration of the tissues by the liquids employed. Drop on to the 

 preparation a small quantity of Fleming's solution, and allow it to remain 

 for four or five minutes. Wash carefully with water, cover with a cover- 

 glass, and examine. 



To make a permanent preparation, replace the water with glycerine 

 by placing a drop of the latter at one side of the cover-glass, and absorb 

 the water from the. other by means of filter-paper. Dry carefully with 

 filter-paper damped with alcohol, and ring with paraffin. 



Fleming's Solittion 



Chromic acid, 1 per cent. . . . .15 volumes 



Osmic acid, 2 ,, . . . . . 4 ,, 



Glacial acetic acid ..... 1 volume 



