- AMOEBAE IN DOGS 1 29 



would migrate eii masse from the gut to the secondary site of infection. 

 Moreover, if the urinary system were secondarily infected, one would 

 not expect to find cysts of the parasite in this situation. It is a general 

 rule that E. hisiolytica does not encyst in the secondary sites of infection, 

 but only in the primary site in the bowel. The occurrence of cysts 

 in the urine, therefore, as recorded by Mactie (1916), and Chalmers and 

 O'Farrell (1917), would — if a correct observation — be surprising. On 

 a priori grounds it seems to me to weaken rather than strengthen their 

 case. The " cysts " of Wright (1917) were clearly, from their size and 

 structure, not cysts of E. hisiolytica. 



Walton's case * I regard as a true case c^f secondary infection of 

 some part of the urinary system with E. histolytica. The negative experi- 

 ments which he made with kittens do not invalidate this conclusion, as 

 similar negative results can often be obtained with undoubted E. histoly- 

 tica from stools. The case of Fischer (1914) was, I believe, in spite of 

 its obviously deficient investigation, a similar case of E. histolytica infec- 

 tion, and I see no reason why Baelz's (1883) original case should not be 

 included in the same category. If it be included, then " Amoeba 

 urogenitalis " Baelz, 1883, becomes a synonym of E. histolytica — which 

 is, I think, the most justifiable interpretation at present. Amoeba vagi- 

 nalis Blanchard, 1885, being another name for the same organism, is 

 then likewise a synonym of E. histolytica. 



I regard Baelz's name "Amoeba urogenitalis" as a provisional 

 descriptive term and not as a Linnaean name subject to the law of 

 priority. He did not determine whether his organism was a new species 

 or not, and his name was proposed in case it should turn out to be new. 

 Chalmers and O'Farrell (1917) refer to "the unpleasant point" that "if 

 the rules of zoological nomenclature are pressed, we ought to call the 

 amoeba of dysentery by Baelz's name." Unfortunately they do not state 

 how they arrive at this conclusion, which seems to me wholly without 

 foundation. If Baelz's name is regarded as valid, then Losch's name 

 ("Amoeba coli") has at least an equal right to recognition. Now the 

 latter was undoubtedly given to the dysentery amoeba. Baelz's amoeba 

 either was or was not the same organism. If it was, and "the rules are 

 pressed," then Amoeba urogenitalis Baelz, 1883, is a synonym of 

 Amoeba coli Losch, 1875, and therefore cannot be used. If Baelz's 

 amoeba was not the same species as Losch's, then it was not the 

 dysentery amoeba, and Amoeba urogenitalis is the name of a different 

 organism. It therefore appears to be impossible to call the dysentery 

 amoeba by Baelz's name — whatever interpretation is adopted. I hold 

 that both these names should be cancelled, on the grounds already slated. 



The Amoebae found in Dogs. 



Amoebic dysentery is said to occur spontaneously in dogs. The 

 parasite which causes it apparently resembles E. histolytica closely, and 

 has been named. It is therefore necessary to consider this organism. 



Kartulis (1891) says that he has seen spontaneous amoebic dysentery 

 in a dog in Egypt ; and that the amoebae were indistinguishable from 

 those in human amoebic dysentery, and produced a similar ulceration 



* I may say that I attach particular importance to this case because of my personal 

 knowledge of the author and of his skill and competence as a protozoologist. 



9 



