PROTOZOA 139 



those of the Heliozoa, and also have elaborate basket-like 

 internal shells of silica. 



Some amcebas cause important diseases of man and other 

 animals. Entamceba histolytica burrows in the wall of the 

 intestine, swallows red blood corpuscles, and is the cause 

 of dysentery ; Entamceba gengevalis is associated with pyhor- 

 rhea alveolaris, a very prevalent disease of the teeth. 



CLASS II. MASTIGOPHORA 



Mastigophorans (Fig. 62, E-G) all have one or more 

 flagella for locomotion, and on this account are commonly 

 known as flagellates. A flagellum is a. slender hair-like 

 process which pulls the cell along by lashing about. In 

 addition to this locomotor appendage, the Mastigophora 

 are generally to be distinguished from the Rhizopoda by 

 the presence of a membrane, or pellicle. This is a thin 

 outer covering which, though it may be pliable, gives the 

 body a more definite form. The simplest mastigophorans, 

 however, lack such a covering. Mastigamceba (Fig. 62, E), 

 for example, is much like an amceba with a single long 

 flagellum. Its body is naked, and it can crawl about by 

 protruding pseudopodia, but it may also swim actively 

 through the water by moving its flagellum. 



Many mastigophorans show relationships to plants. All 

 green plants contain chlorophyll, a substance which is 

 able in the presence of sunlight to elaborate organic com- 

 pounds (starch, etc.) from simple substances like carbon 

 dioxide and water. Such " manufacturing " is known as 

 photosynthesis. Many of the protozoans in this class 

 contain the green chlorophyll and are able to carry on 

 photosynthesis like that in plants. Another indication of 

 relationship between mastigophorans and plants is the fact 

 that the motile stages (swarm spores) of a number of the 

 simpler plants are very much like free living mastigophorans 

 which do not come from plants. We have at one extreme, 

 mastigophorans which are clearly animals, and at the other, 



