1056 PATHOGENIC PROTOZOA 



Diagnosis. While the "history of the case may suggest amoebic 

 infection, the diagnosis can only be made with certainty by micro- 

 scopic examination of the stool. For this purpose the examination 

 should be made as soon after the stool is passed as possible; and 

 in this disease it is usually practicable to have the patient come to 

 the hospital, clinic or office and pass a stool there. It may then be 

 examined immediately. If this is impracticable, the stool may be 

 kept warm and sent to the laboratory in a small glass jar inside 

 a tin pail partly filled with water at body heat; a little cloth or 

 absorbent cotton will hold the hot water and prevent splashing 

 during transit. The stool will show bloody mucous masses, and 

 small drops of this are placed on slides, protected with a cover glass 

 and ringed with warm vaseline to prevent evaporation. The prepara- 

 tion, to be of value, must be thin, and the bloody mucus may be 

 diluted with salt solution if necessary. Except in hot weather, the 

 slide should be examined on a warm stage, or the slide may be 

 warmed by placing heated coins on it, near the cover glass. At least 

 half a dozen slides should be examined before reporting a negative 

 result. Since the entamoebae degenerate and die soon after the stool 

 is passed, it is particularly important, when studying the life history, 

 to use only the very freshest material. Dobell 1 believes that most 

 of the mistakes which have been made in studying the life history 

 of these organisms have been caused by the examination of de- 

 generated or dead parasites, in which both nucleus and cytoplasm 

 may have been abnormal. 



For the study of living amoebae and cysts it is helpful to mix 

 a particle of stool in a drop of salt solution on one slide and in a 

 drop of iodine solution on another. (Iodine should be used as a 

 strong aqueous solution, in potassium iodide the stronger the bet- 

 ter. Dobell.) The iodine penetrates the cyst wall, and if glycogen 

 be present in the vacuoles, gives it the characteristic color; it also 

 acts as a fixative and renders the nuclei easily visible, so that they 

 may be counted and the details of structure made out fairly well. 



Stained preparations are not difficult to prepare, although the 

 process requires some time and care. As in most zoological work, 

 wet, rather than dry, fixation is used. Thin smears are made on 

 cover glasses or slides and before they can dry are covered with 

 or immersed in Schaudinn's fluid. This is a mixture of two parts 



1 Dobell, Clifford, The Amoebae Living in Man, London, 1919. 



