112 THE AMOEBAE LIVING IN MAN 



in a preparation which Col. Wenyon showed me in the summer of 1917. 

 At that time, however, their connexion with the " 1. cysts " was uncertain, 

 though it was one of several possibilities which we discussed. So far as 

 I am aware, Col. Wenyon did not pursue the investigation of these forms 

 further. I continued to look for the amoebae again, however, in other 

 cases ; and I saw them once more in another case which I studied at 

 the end of 1917, and in yet another at the begiiming of 1918 : but J 

 was unable to prove conclusively that the " I. cysts" and amoebae were 

 genetically connected, and on both occasions the amoebae were mostly 

 dead and degenerate. During 191 8 I studied several further cases of 

 infection, but with little better success until the autumn. When my 

 assistant. Miss M. W. Jepps, who had learnt of the "I. cysts" and 

 amoebae from me, left me in the spring, and went to Southampton, I 

 suggested that she should continue to study cases of " I. cyst infection " 

 with a view to clearing up the matter. This she did, and in the late 

 autumn I received from her a preparation containing numerous 

 ** I. cysts " and amoebae, which she had observed alive, from a case 

 which she was studying. A few days later 1 was fortunately able to 

 study the living amoebae, the cysts, and all intermediate stages, in great 

 detail, in another case which Major G. C. Low kindly allowed me to 

 examine. After a very careful study of Miss Jepps's preparation and 

 those which I had myself made from Major Low's case, I felt convinced 

 that the " I. cysts" and the peculiar amoebae are stages in the develop- 

 ment of the same organism. Since then I have encountered the 

 amoebae and cysts again in other cases, and Capt. F. W. O'Connor has 

 very kindly allowed me to study further specimens containing both 

 amoebae and cysts of this species from cases which he investigated in 

 Egypt in 1917. I have now no doubts as to the general correctness of 

 the description given below. There is, I think, no reason to doubt that 

 the " L cyst" — in spite of its remarkable structure — is really the cyst of 

 an amoeba ; and that this amoeba is, moreover, the organism which 

 Prowazek (191 2 «) nnperfectly described, and named Entamoeba biitsclilii. 



Brug (1919), in a paper just published, has returned to the study of 

 this organism and identified it with Prowazek's " Entamoeba Williamsi " 

 — which was really, as has already been pointed out, E. coli. Brug 

 considers that the organism should be referred to the genus Endolimax. 

 The type of this genus is, however, E. nana — an organism whose cysts 

 and nuclear structure are entirely different. His conclusion that the " L 

 cysts are the cysts of Entamoeba Williamsi, Prowasek {sic). The latter 

 should be called : Endolimax Williamsi ", is one in which no proto- 

 zoologist with a systematic knowledge of the amoebae can possibly, 

 I think, concur. 



It is clear that this organism cannot be placed in the genus Entamoeba, 

 on account of its nuclear structure and the characters of its cysts. Nor 

 is there any other genus of amoebae in which it can be correctly placed ; 

 and it thus seems necessary to create a new one to receive it. The name 

 " Pseudolimax," given by Kuenen and Swellengrebel (1917), was not 

 proposed in accordance with the rules of nomenclature as a generic 

 name, and is also inappropriate. As I think it desirable to preserve the 

 historic connexion between the amoeba and Wenyon's " Iodine cysts," 

 which are already so well known to many workers, I therefore propose 

 the generic name given above — lodamoeba — for this organism. Its 

 name, accordingly, becomes lodamoeba biitsclilii Prowazek, 1912. 



