lOD AMOEBA BUTSCHLII 121 



hydrochloride hypodermically. In no case have I found any evidence 

 of the persistence of this amoeba after the administration of a thorough 

 course of emetine in any form. To judge from my own records, 

 /. bi'tischlii may even respond more readily to emetine than E. histolyfica, 

 for I have never 3'et seen a case "relapse" after treatment. This may 

 be a coincidence, however, as I have studied only about a dozen for a 

 sufficient period : and, moreover, all these cases were infected with 

 E. histolytica — for which the emetine was given — and were all apparently 

 cured of infection with this parasite at the same time. 



This behaviour of /. bi'itschlii towards emetine administered to its 

 host is to me extremely puzzling. If emetine were an " amoebicidal " 

 substance, having a specific lethal action upon amoebae generally — 

 as was once believed — such a reaction might even have been predicted : 

 but since it is now highly probable that emetine acts primarily upon 

 the host, and not upon the parasite (cf. Dale and Dobell, 1917), it is 

 difficult to understand how it eradicates infections with /. bi'itschlii. 

 The fact that emetine will not cure an infection with E. coli or E. nana 

 appeared to be clearly correlated with the difference in habit of these 

 species as compared with E. histolytica — neither of them preying directl}'' 

 on its host. But in /. biitschlii we appear to have an organism which 

 lives upon the intestinal contents, like E. coli and E. nana, but which 

 responds to emetine treatment like the tissue-parasite E. histolytica. 

 This may conceivably indicate that there is some peculiarity in the 

 habits of /. bi'itschlii which has not yet been discovered, or that emetine 

 is directly toxic to it. At present the facts seem inexplicable. 



