KNTAMOEBA HISTOLYTICA 23 



— terms which they introduced. Although their work is still a classic 

 from the standpoint of pathology, it added almost nothing to our know- 

 ledge of the amoebae concerned. From a zoological point of view their 

 account of E. histolytica is greatly inferior to Losch's. 



Kovacs (1892) studied 2 cases of amoebic dysentery, and experi- 

 mentally infected 5 kittens with the amoebae, of which he gave a clear 

 description. There can be no doubt that he studied E. histolytica, and 

 that his work was an important confirmation of the earlier observations. 

 He observed typical intestinal lesions in his cats, but failed to cultivate 

 the amoebae. Fuller confirmation of the facts discovered by Losch, 

 Koch, Kartulis, and Councilman and Lafleur, was published soon after- 

 wards by Kruse and Pasquale (1894), as a result of investigations carried 

 out in Egypt. An important new point which they* brought to ligh- 

 was the fact that the amoebae in liver abscess pus — which is bacterio 

 logically sterile, as Kartulis (1887) first showed — are able, if injected />t'r 

 rectum, to infect a cat and give it dysentery. They successfully per- 

 formed this experiment three times out of seven attempts. 



The experiment clearly indicated two important conclusions : namely, 

 that the amoebae associated with dysentery are identical with those found 

 in the pus of liver abscesses, and that the parasites are causally connected 

 with these diseases. A counterpart to this experiment was furnished 

 later by Harris (1901), who succeeded in infecting puppies with the 

 amoebae from a human case of dysentery. Not only did they acquire 

 amoebic dysentery— as in Losch's (1875) experiment — but two of them 

 also developed amoebic liver abscesses subsequently. At the same time 

 it was shown that the bacteria cultivated from the stools of the patient 

 did not cause dysentery when introduced into the dog's intestine. 

 Several workers have since produced amoebic liver abscesses experi- 

 mentally in cats by a similar procedure.! 



The most important zoological work at this early period, however, is 

 that of Quincke and Roos (1893) and Roos (1894), carried out in Kiel; 

 for it not only showed that more than one species of amoeba inhabits 

 the human bowel, but it also showed with equal clearness how these 

 species may be differentiated, and how man becomes infected with them. 

 It is astonishing that this fundamentally important work has hitherto 

 received so little attention. 



Although Quincke and Roos studied only a single case of amoebic 

 dysentery, they studied it very carefully ; and they controlled their 

 observations by a study of the amoebae occurring in non-dysenteric cases. 

 The amoebae found in the patient suffering from dysentery are -well 

 described, and recognizably figured. :|: The sharp demarcation between 

 the ectoplasm and the endoplasm, the appearance of the nucleus, the 



* Schuberg (1893) states that this experiment was first performed by Kartulis (1891). 

 This author says, however, that he cultivated the amoebae from a hepatic abscess — in 

 pure culture, free from all bacteria : and with this culture he claimed to have infected 

 a kitten, which acquired typical amoebic dysentery and showed typical ulceration of its 

 %\Apost moriciii. In the light of our present knowledge the interpretation of this result 

 by no means free from difficulties. 



t Craig (1905), Huber (1909), Wenyon (1912), Baetjer and Sellards (I9i4<j), Dale 

 and Dobell (1917). 



X By Roos (1894). The woodcuts in the first communication by Quincke and Roos 

 (1893), are very crude. 



