4 BEANCH PROTOZOA 



It is said that in the bodies of some Radiolaria are found unicellular 

 Alga;, or microscopic plants, which furnish, even in this low stage of life, 

 an example of symbiosis, or the living together of different kinds of organisms 

 for mutual benefit. 



CLASS n. MASTIGOPHORA 



The Eugle'na is a representative of the second class of Pro- 

 tozoans (Mastigoph'ora). It has a more fixetl arrangement 

 of parts than the Amoeba. The cell is surrounded by a delicate 

 membrane perforated at the blunt anterior end b\- a funnel- 

 shaped mouth through which the food passes into the body suV)- 

 stance. From the base of this mouth the protoplasm extends 

 out in a long fiagellutn which, by its lashing, propels the body 

 forward, and produces currents of water which bear food into 

 the mouth. Back of the mouth is a tiny pigment spot beside a 

 clear space which is sensitive to light. 



CLASS in. SPOROZOA 



This class consists of parasitic protozoans. The Gregari'na 

 is parasitic in the intestines, reproductive organs, or, rarely, in 

 the body cavity of invertebrates, such as crayfish, insects, and 

 worms. It absorbs hquid food from its host and has no mouth 

 nor pseudopodia. One or two individuals become encysted and 

 then break up into a number of minute portions called spores. 



The Haemosporid'ia are sporozoans which live in the blood-corpuscles of 

 vertebrates. In man they arc the germs which produce malaria. The 

 malaria-producing protozoans spend part of their life in man and part in a 

 certain genus of mosquito Anopli'eles). A\hen this mosquito sucks the 

 blood of a malarial patient the germs are taken into the slomach of the 

 mosquito. " After fertilization the oosphere wanders into the intestinal 

 wall of the mosquito, grows larger, encysts, and produces man\- sporo- 

 blasts, which in time form many sporozoitcs." These ]iass out with the 

 saliva of the female Anoph'eles as it " bites " another person, and thus the 

 germs of malaria are transferred to his blood, where, under iirojier condi- 

 tions, they multiply rapidly, and fever results. It is evident that the bite 

 of this mosquito does not cause malaria unless the niiis(iuito is itself in- 

 fected with the germs. 



Yellow fc\'er is lii'lie\-ed to be caused by another sporozoan carried by -i 

 ilifforcnt genus of mosquito (Stcgoinij'ia). 



