232 TROPICAL MEDICINE AND HYGIENE 



they are tougher and stronger than those of the A. coll. 

 The nucleus is not readily visible and is poor in 

 chromatin, and therefore does not stain deeply in stained 

 preparations. Schaudinn describes the multiplication as 

 different from the E. coli. 



The whole cell does not form a cyst, but a series of 

 buds are formed externally, each of which becomes a 

 latent encysted form. These observations have not been 

 confirmed, and (by many) the distinctions between . coli 

 and E. histolytica are doubted. Many consider that this 

 parasitic amoeba is E. tetragena. In the encysted forms 

 there are never more than four nuclei. It is highly 

 pathogenic to cats and may in them cause liver abcesses. 

 In the active moving forms it is indistinguishable from 

 E. histolytica. Probably E. histolytica and E. tetragena are 

 the same, and possibly E. minuta. 



E. histolytica or tetragena may enter the subcutaneous 

 tissues and be carried to various parts of the body, such 

 as the liver, spleen, and kidneys, and there may cause the 

 formation of abscesses. These abscesses are slowly 

 formed and may attain enormous size, containing many 

 pints of pus. They are usually single, but two or three 

 are not rare. The pus in such abscesses is white, yellow, 

 or may be chocolate in colour. It is a very thick, slimy 

 pus. The walls of the abscess are rugged, and as a rule 

 there is little formation of fibrous tissue around, though 

 there is an area of intense congestion. In the pus from 

 such an abscess no bacteria are found, either on examina- 

 tion or by culture, in the majority of cases. In others, 

 the minority, there are bacteria, but these are not of any 

 uniform species. These facts are taken to show that the 

 amoebae are pyogenic, and that for the formation of pus 

 no bacterial aid is necessary. Others particularly state 

 that in early abscesses bacteria are to be found, but admit 

 the possibility that they have been carried by the amoebae, 

 and that in the large sterile abscesses these bacteria have 

 died out. 



The amoebae are very scanty in the pus in the abscess, 



