182 AHAHTHROPODA 



Amoeba may be recognized by its slow crawling and fre- 

 quent changes in shape as it puts forth the blunt processes 

 called pseudopods. It appears like a mass of granular color- 

 less protoplasm streaming along inside of & transparent sac 

 known as the ectosarc. It has no mouth but secures food 

 by wrapping itself about any organic material which then 

 passes through the ectosarc into the soft protoplasm, called 

 endosarc, capable of digesting it. The products excreted 

 by the lungs and kidneys of the higher animals are also 

 excreted by the one cell forming the amoeba. 



For continued study, the Amoeba should be mounted as 

 directed for Paramcecium. Some of them may then be 

 seen taking on globular shapes and surrounding themselves 

 with a kind of cyst or coat. In this condition they are said 

 to be encysted, and are capable of thus existing in a dried 

 state for months. While encysted they often divide into 

 several parts called spores, each of which upon the bursting 

 of the cyst forms a complete animal. They also reproduce 

 by binary fission, but this method is not common. 



Parasitic Forms. Several species of protozoans are 

 dwellers in the higher groups of animals from worms to 

 man. Amceba coli lives in the intestines of man and causes 

 a severe kind of dysentery. Plasmodiwn malarice is always 

 present in the blood corpuscles of patients suffering from 

 any of the malarial fevers. Mosquitoes of the genus 

 Anopheles (Fig. 371) transfer the parasites from the sick 

 to the healthy, and thus a large part of an entire community 

 may become infected with this germ. It belongs to the 

 class Sporozoa, which is so named because the animals in 

 reproducing divide into a number of small bodies called 

 spores. 



