644 AMCEBIC DYSENTERY 



cases in the Philippine Islands and in America. It has been 

 shown experimentally by Hartmann and by Werner to have 

 pathogenic properties to cats. There is little doubt that it is 

 a cause of " tropical dysentery," in what proportion of cases 

 remains to be determined; later observations show that it is 

 commoner than was formerly supposed. 



The entamoeba coli is an organism of about the same size as 

 the previous, but varies greatly; the measurements given by 

 Hartmann are 10-50 /x. When at rest it shows no differentia- 

 tion into ectoplasm and endoplasm, and the nucleus, usually situ- 

 ated in the centre, shows a highly refractile membrane with 

 chromatin masses scattered in the interior. During amoeboid 

 movement some delicate processes of ectoplasm come into view. 

 Red corpuscles are rarely found in the interior and only in 

 small numbers. The cellular changes in the encysting of the 

 entamoeba coli have also been worked out by Schaudinn. They 

 are of a somewhat complicated character, involving the formation 

 of reduction bodies and copulation of nuclei, but the ultimate 

 result is the formation of a fairly large cyst, which contains 

 eight small cells. The process of cyst formation accordingly in 

 the three organisms is of a widely different character. No one 

 has been able to produce distinct lesions by means of the 

 E. coli, and it must be regarded as a harmless inhabitant of 

 the bowel. 



The descriptions of the encystment of amoebae from cases of 

 dysentery as given by other observers differ considerably. In 

 the majority of the investigations published no process of encyst- 

 ment of buds on the surface of the amoeba has been observed, 

 the whole cell becoming enclosed in a cyst, which is of consider- 

 able size. The facts already ascertained point strongly to there 

 being other pathogenic species which have not yet been satis- 

 factorily 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 amceb?e 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 amoebse 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. Elmassian found a small 

 amoeba in cases of dysentery in South America, to which he gave the 



