PATHOGENIC AMOEBA 485 



Clinical Diagnosis 



1. A drop of the dysenteric discharge (the mucous portions 

 should be chosen from the stools), pus, or, better, a scraping from 

 the wall of the abscess, diluted, if necessary, with a little warm 

 (37 C.) physiological salt solution, is placed on a slide, covered 

 with a cover-glass, and examined microscopically with a j- or J-inch 

 objective. The amoebae will be readily recognised, and may be 

 examined more critically with a ^L-irich oil-immersion. To be 

 certain that the bodies are amoebae, the amoeboid movements must 

 be observed by keeping the preparation on a warm stage. 



The stools should be fresh, unmixed with urine, collected in a 

 warmed bed-pan, and kept at blood-heat until examined, which 

 should be done as soon as possible. 



2. The living amoebae in the stools may be stained by the irriga- 

 tion method with a weak (|-1 per cent.) aqueous solution of neutral 

 red. Preparations may also be stained by irrigation with methyl- 

 ene-blue and Beale's carmine ; the latter stains the nucleus, the 

 former does not. The preparation may be rendered permanent 

 by washing away the excess of stain, and running in some 50 per cent, 

 glycerin by irrigation. 



3. Probably Heidenhain's iron-haematoxylin method is the best 

 for staining this and other protozoa : 



(a) Make smears of the material and drop while wet into the 

 fixative two parts of saturated aqueous mercuric chloride solution, 

 one part of alcohol, with a few drops of glacial acetic. They remain 

 in this for ten minutes. 



(6) Wash in weak spirit and then in weak spirit coloured with 

 iodine, and finally wash in distilled water. 



(c) Treat with 4 per cent, iron-alum solution for six to ten hours. 



(d) Stain in Heidenhain's hsematoxylin for at least six hours. 



(e) Differentiate in 1 per cent, iron-alum, watching microscopi- 

 cally. 



(/) Wash well in tap-water, pass through alcohol and xylol, and 

 mount. 



4. Twort's stain may be used for sections. . The stain (which is 

 a compound neutral red and light green preparation) is best made 

 by rubbing up 0-25 grm. of the stain (Griibler's) with some clean 

 sharp sand in a mortar ; this prevents the stain going into a sticky 

 mass when the alcohol is added. To the powder so obtained is 

 now added some purest methyl alcohol (Merck's), acetone-free, 

 containing 5 per cent, by volume of glycerin. Rub up well to 



