112 HUMAN INTESTINAL PROTOZOA IN THE NEAR EAST 



The acute cases seem to differ from the carrier cases only in 

 degree, for between the attacks of dysentery the acute cases are 

 actually in the carrier condition passing amoebae and cysts which 

 are indistinguishable from those passed by the carriers who have, 

 perhaps, never had an attack of dysentery. The view which has 

 already been expressed above, that it seems probable that all the 

 carriers have some ulceration of the intestine, affords the best 

 explanation of this difference in the action of emetin in the acute 

 and carrier cases. Certain of the carrier cases have no symptoms 

 whatever and it is possible that in them the ulceration is at a 

 minimum. Other carriers have had an attack of dysentery and 

 from time to time pass mucus in the stool. In them the ulceration 

 is probably more extensive. With a still more serious condition 

 of ulceration the attacks of dysentery are more frequent and we get 

 the condition of the typical chronic amoebic dysenteric who has 

 repeated attacks of dysentery. During these he passes blood and 

 mucus with active amoebae containing red blood cells. Between the 

 attacks the stool is always soft, and contains varying quantities of 

 mucus, while E. histolytica cysts and amoebae are found in enormous 

 numbers. The most serious condition is seen in cases like that of 

 Smith where the dysentery is practically constant and encysted 

 forms of E. histolytica never occur in the stool. The amoebae are 

 always in the free condition and frequently show included red blood 

 corpuscles. These cases with extensive ulceration are naturally 

 much more difficult to treat than the simple carriers who have only 

 very slight intestinal lesions. It seems probable that the varying 

 condition of the gut rather than any other factor is responsible for 

 the variation in the response to emetin treatment. We do not 

 know how the emetin reaches the amoebae or exactly how it is 

 excreted, for cures have been effected both by hypodermic injection 

 of emetin as well as by emetin by the mouth, but if the drug is 

 usually brought into contact with the amoebae by way of the circula- 

 tion then it is perhaps understandable that, in cases with the 

 extensive ulceration of the chronic amoebic dysenteric, with old 

 fibrotic ulcers and thrombosed vessels, the emetin is unable to 

 reach many of the amoebae for purely mechanical reasons of 

 impaired circulation. It is possible that in this condition the 

 amoebae in certain situations can be reached and destroyed if emetin 

 is given by the mouth instead of by injection. 



(d) Are there Emetin-resistant Strains of Amcsba ? It has been 

 suggested that, in certain cases, the amoebae owing to past in- 

 efficient emetin treatment have acquired the power of resisting the 



