448 



EVOLUTION OF ANIMALS 



Part V 



this and certain other conditions, the symptoms of malignant tertians are quite 

 different from those commonly supposed to belong with malaria. "Blackwater 

 fever" is probably a type of malaria caused by Plasmodium falciparum. 



Treatment of Malaria by Drugs. A considerable number of drugs have been 

 found to have antimalarial effects. The four which arrest the development of 

 the merozoites of all species of Plasmodium and in sufficient doses are cura- 

 tive in the malaria of Plasmodium falciparum are quinine, atabrine, chloro- 

 quine, and paludrine. More recently developed than any of these is the power- 

 ful antimalaria drug, darasprim, which holds the possibility of eliminating the 

 disease. 



Class Ciliata 



All ciliates bear cilia at some period of their lives; many throughout life 

 (Fig. 21.16). Ciliates are complex, and specialized mainly for independent 

 living. They live on or in many plants and animals, myriads of them in pro- 

 tecting capsules on grass blades. Sheep, cattle and other cud-chewers swal- 

 low them into the first stomach or rumen along with great numbers of bac- 

 teria. Ciliates and bacteria become active in the warmth and moisture of the 

 rumen and the bacteria provide a rich food supply for the protozoans 

 (Fig. 11.14). Ciliates always abound in all healthy cud-chewers after they are 

 old enough to eat grass. They disappear as the food is moved on into other sec- 



FiG. 21.16. Two colonial protozoans that like paramecia are dependent on cilia 

 for the intake of food and are common residents of fresh water. Left, Vorticella, 

 bell animalcule. Right, Epistylis, often attached to aquatic insects. (Left, courtesy, 

 Conn: "Protozoa of Connecticut," Conn. State Geol. and Nat. Hist. Survey Bull. 

 %2, 1905. Right, courtesy, Hyman: The Invertebrates, vol. 1. New York, Mc- 

 Graw-Hill Book Co., 1940.) 



