METHODS OF EXAMINATION 609 



From the above facts, all of which have received ample 

 confirmation, there can be no doubt that the amoebae described 

 are the cause of the form of dysentery with which they are 

 associated. As already stated, much information is still required 

 as to the different species of pathogenic amoebae and as to the 

 means of distinguishing them, if this is possible, from harm- 

 less forms. In this connection it is interesting to note that 

 Musgrave and Clegg obtained pathogenic effects with amoebae 

 resembling the E. coli. But the causal relationship of amoebae 

 to dysentery has been completely established by the anatomical 

 and experimental evidence. It is also of importance to note 

 that the serum of patients suffering from amoebic dysentery 

 gives no agglutinating reaction with Shiga's bacillus of dysentery 

 (vide p. 384). 



It is important to note that cases of amoebic dysentery have 

 been recorded both in France and England in patients who have 

 never resided outside these countries. 



Methods of Examination. The faeces in a case of suspected 

 dysentery ought to be examined microscopically as soon as 

 possible after being passed, as the amoebae disappear rapidly, 

 especially when the reaction becomes acid. A drop is placed 

 on a slide without the addition of any reagent, a cover-glass is 

 placed over it but not pressed down, and the preparation is 

 examined in the ordinary way or on a hot stage, preferably by 

 the latter method, as the movements of the amoebae become 

 more active, and it is difficult to recognise them when they are 

 at rest. Hanging-drop preparations may also be made by the 

 methods described. Dried films are not suitable, as in the 

 preparation of these the amoebae become broken down; but 

 wet films may be fixed with corrosive sublimate or other 

 fixative (vide p. 96). In sections of tissue the amoebae may be 

 stained by methylene-blue, by safranin, by haematoxylin and 

 eosin, and iron hamnatoxylin, etc. Benda's method of staining 

 with safranin and light-green is also a very suitable one. 

 Sections are stained for several hours in a saturated solution 

 of safranin in aniline oil water (p. 105), they are then washed 

 in water and decolorised in a J per cent, solution of light-green 

 in alcohol till most of the safranin is discharged, the nuclei, 

 however, remaining deeply stained. In this method the nuclei 

 of the amoebae are coloured red (like those of the tissue cells), 

 the protoplasm being of a purplish tint. 



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