AMCEBIC DYSENTERY. 533 



administered, but they obtained a fatal result in two out of four cases 

 when the cyst-like forms were given. From this fact they infer that the 

 latter are probably a cystic stage of the former, and that the former are 

 destroyed in the gastric contents. This practically constitutes the only 

 important evidence that a cystic stage of the organism has really been 

 observed. These observers found that the cyst-like bodies were still 

 present even after the material had been kept for two or three weeks. 



From the above facts, all of which have received ample confirma- 

 tion with the exception of the statements regarding the cyst-hke forms, 

 there can be little or no doubt that the amcebse described are the causes 

 of the form of dysentery with which they are associated. We are still igno- 

 rant, however, as to their life history outside the body, and the modes by 

 which infection is produced. Further, in any case where they act as 

 the primary agent, secondary inflammatory changes in the intestine may 

 be produced by the action of various bacteria. 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. 349). 



Methods of Examination. — The faeces in a case of suspected dys- 

 entery ought to be examined microscopically as soon as possible after 

 being passed, as the amcBbse disappear rapidly, especially when the 

 reaction becomes acid. A drop is placed on a slide without the addi- 

 tion 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 films may be fixed with corrosive 

 sublimate or other fixative (vide p. 90) . In sections of tissue the amoe- 

 bae may be stained by methylene-blue, by safranin, by hasmatoxylin and 

 eosin, 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. loi), they are then 

 washed in water and decolorised in a ^ 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. 



