Chap. 21 



No solid 

 food 



THE PROTOZOANS 



WAYS OF LIVING 



Much solid food 



429 



) 5. 



Colonies 



Parasites 



Fig. 21.3. Ways of living. Free living and solitary. 1, Euglena is brilliant green 

 with chlorophyll and makes its own food by photosynthesis. 2. Pelomyxa paliistris 

 is relatively very large and ameba-like. It consumes so many small organisms that it 

 may have a hundred food vacuoles at one time. /// colonies. In spheres of trans- 

 parent cellulose, 3, Pandorina and 4, Eudorina. 5, Giardia intestinalis and related 

 species live in the intestines of various vertebrates including man. A, active form 

 with two nuclei and eight flagella. B, side view of the active animal attached to the 

 lining of the intestine. C, two young animals that are about to separate. (Courtesy, 

 Jahn and Jahn: The Protozoa. Dubuque, Iowa, Wm. C. Brown and Co., 1949.) 



cockroaches {Cryptocercus punctulatus) and termites have a similar relation 

 with certain flagellates. 



Their minute size and preference for fluid environments open the way for 

 protozoans to be successful parasites. Among the parasites are species of 

 Plasmodium that in one stage of their lives invade human red blood cells and 

 cause malaria, and in another live in anopheiine mosquitoes without doing the 

 latter any apparent harm. Entameba histolytica, the most important intestinal 



