ENTAMCEBA 



63 



of the food of its host. It never attacks the tissues of its host and 

 is harmless, and possibly sometimes even beneficial by keeping 

 down the bacteria. Its life-history differs considerably from that 

 of Amceha proteus. In the intestine it reproduces by binary fission, 



Fig. 35. — Entamceba histolytica. 



a and b, Amoebse as seen in fresh stools, showing blunt ectoplasmic 

 pseudopodia, non-contractile vacuoles, ingested red corpuscles, 

 and in a, nucleus ; c, an amoeba as seen in a fixed preparation ; 

 d section of wall of liver abscess, showing an amoeba of spherical 

 form. The rounded amoebae on this plate must not be confused 

 with the encysted form. 



and some of the small products of fission become rounded, expel 

 all their contained food, and encyst. In the cyst there is at first 

 a single nucleus, but after proceedings in which some of its 

 chromatin is lost, while a large glycogen-filled vacuole temporarily 

 appears in the cytoplasm, this divides to form eight. The ordinary 

 EntamcehcE die in the faeces. So do the cysts if the faeces dry. 



