106 ONE-CELLED ANIMALS— PHYLUM PROTOZ OA 



gestive system. Here they lose their thick walls and start to multiply. 

 They penetrate the inner lining of the intestine and often form ulcers 

 which cause an attack of dysentery. Infected persons, if not promptly 

 treated, pass numerous cysts which may spread the disease. 



Stalked Protozoa — The Suctoria 



There are a number of protozoans which are ciliated in the early stage 

 of their life, but lose the cilia and become attached to some object by means 

 of a long stalk when they grow older. They capture food, which often 

 consists of other protozoans, by means of tentacles. Some of these tentacles 

 have small suction cups on the end, which characteristic gives the class its 

 name. Young animals are formed from a portion of the parent cell. 

 They develop cilia, swim around for a time, and then form a stalk and 

 turn into the adult form. This is not usually considered as an important 

 class of the Protozoa. 



Classification of the Protozoa 



We have now surveyed some representative forms in the phylum 

 Protozoa. In order to keep up with the classification of the animal king- 

 dom as we go along we will list the important classification groups at the 

 close of each chapter, together with the derivation of the words when such 

 derivations are of value in learning the words. This will give a systematic 

 outline of the animals studied in each chapter dealing with the survey of 

 the animal kingdom. 



Phylum. Protozoa (Gr. protos, first; coon, animal; refers to the fact that 

 these are the first or simplest animals). 

 Class A. Sarcodina (Gr. sarx, flesh; refers to the false feet made from 

 the animal's flesh). 

 Genus 1. Amoeba (Gr. amoibe, change; refers to the Amoeba's 

 power to change its shape), 

 species a. proteus (the name of an old Greek sea god that 

 could change his shape). 

 Genus 2. Endamoeba (Gr. endon, within ; amoibe, change ; refers to 

 the amoeba living within another animal's body), 

 species a. coli (En. colon, large intestine), 

 species b. histolytica (Gr. histo, tissue; lysis, dissolve; refers 



to the tissue-dissolving properties of this species), 

 species c. gingivalis (L. gingiva, the gums of the mouth ; refers 

 to the habitat of this species on the gums). 



