PAKT II. CHARACTERS AND DIAGNOSIS 51 



amoebae and a fortnight later had another attack of amoebic 

 dysentery. Case Blair recovered in the same way under emetin 

 treatment, but amoebae and cysts of E. histolytica were present a 

 fortnight after treatment was stopped. Both these cases had had 

 repeated attacks of dysentery before coming under the present 

 observation. 



If an individual who is a carrier of E. histolytica, and is passing 

 encysted forms in the stool, relapses into acute dysentery one 

 should be able to observe the transition if the case is examined 

 early enough. A case of this kind was seen under very favourable 

 conditions for this examination. A patient (case Ball) was one of 

 the hospital staff who had had repeated attacks of dysentery and 

 much emetin treatment. He was suddenly taken ill with 

 dysentery and the stool was examined almost at once. It consisted 

 of two parts, a fsecal portion and a blood and mucus portion. The 

 former contained numerous cysts of E. histolytica with some 

 amoebae, and the latter numerous active amoebae with included red 

 blood corpuscles. It was evident that this was an instance of a 

 carrier relapsing into a condition of acute amoebic dysentery. He 

 was treated with emetin and the symptoms and infection vanished, 

 but ten days later cysts of E. histolytica were again present. 

 Another course of emetin was given and the infection again dis- 

 appeared, only to return with cysts and amoebae three weeks later. 

 In two other cases (Rushforth and Dorter) a similar condition of 

 affairs existed at the first examination, there being acute dysentery 

 with active amoebae containing red blood corpuscles and associated 

 with cysts of E. histolytica. Both these cases relapsed after 

 emetin, and cysts of E. histolytica appeared in the stools. In the 

 case of Dorter there was a previous history of much dysentery, 

 whereas with Rushforth there had been no previous dysentery, the 

 patient having only been in the country a short time. 



In the majority of cases of actual amoebic dysentery cysts of 

 E. histolytica cannot be discovered, though an examination of a 

 faecal portion of the stool, if such be present, may reveal them 

 when only free amoebae are to be found in the blood and mucus part. 

 Cases like those recorded above leave little room for doubt that the 

 cysts of E. histolytica are definitely related to and derived from 

 the amoebae which give rise to the dysenteric symptoms. One case, 

 however, must be mentioned, for in it no cysts of E. histolytica 

 could be found at any time, though there were repeated attacks 

 of dysentery which were cured temporarily by emetin treatment. 

 This case, Smith, was followed most carefully from April 5 to 



