CULTIVATION 605 



whole cell becomes enclosed in a cyst, which is of considerable 

 size. The facts already ascertained point strongly to there being 

 more than one pathogenic species which have not yet been 

 satisfactorily distinguished. 



The whole subject of the classification and means of distinguishing the 

 species of pathogenic and non-pathogenic amoebae is still in a very un- 

 satisfactory state, and much further work is necessary. We may, however, 

 refer to some of the facts recorded. Musgrave and Clegg, working in 



(Manila, cultivated amoebae from drinking water and from various other 

 external sources as well as from cases of dysentery, and found that they 

 possessed similar characters. The cysts as shown in their photographs 

 are of fairly large size, and do not correspond to Schaudinn's description. 

 By means of amoebse, cultivated from sources apart from dysentery, they 

 were able to produce dysenteric symptoms and lesions in monkeys, 

 Lesage cultivated amoebic from cases of dysentery in Saigon and Toulon, 

 and found that the process of encystment as studied in agar plates agreed 

 with the account given by Schaudinn. Craig, as the result of studies on 

 amoebae in San Francisco, confirms the work of Schaudinn with regard to 

 E. coli and E. histolytica. Viereck found an amoeba in two cases in 

 Hamburg which resembled E. coli, from which, however, it differed in 

 its cysts containing only four cells. He gave to it the name E. 

 tetragena. Hartmann found the same organism in African dysentery, and 

 was able by means of it to produce dysentery in cats, though the disease 

 was milder than with E. histolytica. !Noc, working in Cochin-China, 

 cultivated nim.-l:< from the intestines in dysentery, from liver abscesses 

 and from drinking water, and found that they all had the same 

 characters. The process of encystment was different from that described 

 by Schaudinn, the whole cell becoming enclosed by the cyst. In 

 addition to the ordinary method of fission, it formed, numerous small 

 cells or merozoites by a process of budding within the protoplasm ; these 

 afterwards becoming free. 



Cultivation. Various attempts have been made to cultivate 

 the amoeba of dysentery, and Kartulis considered that he obtained 

 growth in straw infusions. Within recent years cultures of 

 amoebae in association with various bacteria have been obtained 

 on agar media by various workers, e.g. Lesage, Musgrave and 

 <']'"_ r L r . X.H-, ami "tlirr-. |-'.,r this |iir]m-.i- a plain a^ar without 

 I>eptone is used, and its reaction is made distinctly alkaline to 

 phenolphthaleine. The presence of .bacteria seems to be 

 essential for the growth of the amoeba?, and it is found that some 

 species favour growth whilst others act prejudiciously ; amongst 

 the former may be mentioned the sp. choleras, b. subtilis, and 

 various HUM nters of the coli group, though organisms from a 

 great variety of sources have been found to be equally efficient. 



In such cultures, which are most conveniently made in Petri 

 dishes, the stages of growth and encystment of the amoebic can 

 be readily studied; the organisms seem to flourish best at a 



