192 FAMILY: AMCEBIDiE 



diately reveal amoebae even in cases which have proved negative after 

 many examinations of the faeces. 



Some observers have attempted to discover a means of diagnosis in 

 the microscopic appearance of the cells in the stools of amoebic dysentery 

 cases, but apart from the amoebse there is nothing characteristic of the 

 condition. As a rule there occur a certain number of cells, including 

 degenerating epithelial cells, macrophages which have been discharged 

 from the ulcers, and some pus cells. They are usually present in com- 

 paratively small numbers, and it is only rarely that the stool contains 

 the enormous number of cells usually seen in acute bacillary dysentery. 



Thomson, J. G. (1918), and Acton (1918) drew attention to the frequent 

 presence of Charcot- Ley den crystals in the stools of amoebic dysentery 

 cases, and the latter observer concluded that their presence was pathog- 

 nomonic of an infection with E. histolytica. Thomson, J. G., and Kobert- 

 son (1921 and 1921a) have published an account of observations which 

 tend to confirm the earlier conclusions. It is possible that Charcot- 

 Leyden crystals appear in any chronic ulcerative condition of the large 

 intestine, and that their association with E. histolytica is a result of the 

 amoeba being the most frequent cause of such a condition. 



It has been noted above that E. histolytica may find its way to the 

 liver, spleen, or even the brain, and there give rise to abscesses. In these 

 situations the process of development is like that in the deeper tissues 

 of the intestinal lesions. Only the large amoebae are found, and there 

 seems to be no tendency to the production of the small, precystic amoebse 

 or cysts, which have never been demonstrated in these situations. 



Wherever E. histolytica occurs in the tissues there is no tendency for 

 the area of invasion to be limited by the formation of fibrous tissue. On 

 this account the abscesses of the liver are not limited by a fibrotic wall, 

 as occurs in the case of chronic bacillary abscesses. If a section of the 

 wall of an amoebic abscess is examined, it will be seen that there is a 

 gradual transition from normal tissue to the completely necrotic area on 

 the surface of the abscess wall. The amoebse are found to be most 

 numerous in what may be called the intermediate zone. On this account 

 the examination of the pus which first discharges from an amoebic abscess 

 of the liver may reveal no amoebse. After a day or two, when apparently 

 the surface of the abscess is breaking away and being discharged, amoebse 

 may appear in the discharge in large numbers. These amoebse have the 

 same character as the larger forms found in the intestinal ulcers. 



A number of records of the presence of amoebse in the urine have been 

 published. In the majority of cases these are more than doubtful, but 

 in one or two instances, as in the cases recorded by Walton (1915) and 

 Petzetakis (1923), it seems safe to suppose that the observers were actually 



