PHYLUM PROTOZOA 



71 



It is carried from one person to another by a certain species of 

 tsetse- fly, Glossina palpalis (Fig. 45). The parasite, after gain- 

 ing access to the blood of a human being, multiplies with re- 

 markable rapidity. The nervous system of the patient is af- 

 fected either directly or by a poison secreted by the parasites. 

 The disease may last several months or even years. Irregular 



Fig. 45. — Glossina palpalis, the tsetse fly, which carries the germs 

 of sleeping sickness. (From Calkins.) 



fever soon follows infection, and later general debility sets in. 

 The victim exhibits an increasing tendency to sleep, gradually 

 wastes away, and finally dies. 



Sporozoa. — Of the Sporozoa which affect man, the malarial 

 fever parasite is the most important (pp. 50-52). 



Infusoria. — Two species of parasitic Ciliates which are found 

 in the intestine of human beings are thought by some investi- 

 gators to be important in catarrhal inflammation of the intestine. 

 They are Balantldium coli and B. minutum. These parasites 



