THE DYSENTERIES— AMCEBIC 



Pseudopodia 



Vacuoles ... 

 Nucleus 



Chromidian bodies 

 ■Contents ... 



Motility 



Multiplication 



Pathogenicity 



It. tetrageiia cysts 



Large and easily distinguished. 

 Consists of ecto- and endo- 



plasm 

 Many 



Often absent, when present its 

 structure is hidden. Nuclear 

 nien)brane not well defined. 

 Changes position markedly. 

 Never more than four nuclei 

 — hence " tetragena" 



There is little chromatin 

 Erythrocytes, bacteria, pus 



cells, crystals 

 Great progressive motility 

 In intestine by fission and bud- 

 ding. Buds small, 4jU with 

 two nuclei. (^*n hard faeces 

 and outside body resistant 

 spores are formed without 

 encystment. These develop 

 when ingested. 

 Pathogenic, penetrates the 

 tissues and often causes liver 

 abscess 



E. coll cysts 



Hard to distinguish 

 Entirely ectoplasm 



Never more than one. May be 

 absent 



Almost always present, with 

 well defined nuclear men-.- 

 brane and other structures. 

 When organism moves, nu- 

 cleus retains its relative 

 position. May be up to 

 eight nuclei 



There is much chromatin 



Rarely cells or organisms 



Motility limited 



In intestine by binary fission 

 and multiple fission into eight 

 amoebulac. These are set free 

 when ingested 



Never pathogenic and never 

 seen penetrating the tissues. 

 Never causes liver abscess. 

 They are limited to the large 

 intestine and caecum. 



LIFE-HISTORY. 



The E. tetragena reproduces in tliree ways : — 



(i) By binary fission, discovered bv Schaudinn. The nucleus 

 divides by amitosis into two, and then the cytoplasm splits 

 into two ecjual daughter cells. 



(2) By gemmation. — Found by Schaudinn to be more frequent 



than binary fission. The nucleus divides by amitosis into 

 two or more daughter nuclei with a portion of the cytoplasm, 

 which then separates off from the mother cell, the daughter 

 cells being the smaller. 



(3) By spore formation. — The chromatin becomes diffused, collects 



around the periphery, the nucleus disappearing. The ecto- 

 plasm forms into small knob-like processes, each containing 

 several chromidia. These become separated off and are 

 surrounded with a yellowish-brown envelope, forming spores 

 ready for infecting a new host (Schaudinn). These are 

 surrounded by a cyst wall which is broken down when 

 ingested and the eater infected. 

 These E. tetragena are found in the faeces, intestinal contents, 

 debris from dysenteric ulcers, liver abscesses, mucosa and submucosa 

 of intestinal wall. On the warm stage th^y show active amoeboid 

 movement. The cyst resists drying. 



