542 AMCEBIC DYSENTERY 



been supplied by experiments of Schaudinn. Dysenteric material 

 was obtained from China, and portions of it which were found 

 to contain the cysts were thoroughly dried. Some of this 

 material was given with food to cats by the mouth, and typical 

 dysentery resulted, the amoebae being found in the stools. No 

 results follow when the material ingested merely contains the 

 vegetative form of the organism, as it is readily destroyed in the 

 contents of the stomach. 



Investigations with regard to entamoeba coli show that it is 

 a harmless organism and that it is frequently present in the 

 intestines of healthy individuals. Schaudinn found that in East 

 Prussia as many as 50 per cent of the population were infected 

 with it. The administration of the amoebae, or of the cysts by 

 the methods mentioned above, produces no result in animals. 

 It has, however, been shown that when the eight-celled cysts 

 are swallowed by persons who are free from the parasite, the 

 entamceba coli appears in the large intestine in a comparatively 

 short period of time. It accordingly appears that in the case of 

 both organisms it is the cysts alone which give rise to infection. 



From the above facts, all of which have received ample 

 confirmation, there can be no doubt that the amoeba described 

 is the cause of the form of dysentery with which it is associated. 

 We are still ignorant whether the organism has any life history 

 outside the body, but it has been shown that the cysts have 

 high powers of endurance and almost certainly form the means 

 of infection when they are swallowed in drinking-water or in 

 food. 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. 348). 



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. 88). In 

 sections of tissue the amoebae may be stained by methylene-blue, 

 by safranin, by haematoxylin and eosin, etc. Benda's method of 



