SPOROZOA. 183 



INFUSORIA (CILIATA.) 



The bodies of Infusoria are oval and may be free or attached to a 

 stalk-like contractile pedicle, as with Vorticella, or they may be sessile. 

 The cilia, which are characteristic, may be markedly developed around 

 the cystostome (mouth) and serve the purpose of directing food into the 

 interior, while others act as locomotor organs. The body is enveloped by 

 a cuticle which may only have one opening or slit, to serve as mouth ; 

 or it may have a second one, a cytopyge or anus. Usually the fecal 

 matter is ejected through a pore which may be visible only when in use. 

 They usually have a large nucleus and a small one. Infusoria tend to 

 encyst when conditions are unfavorable. 



Balantidium coli. This is the only ciliate of importance in man. 

 It is a common parasite of hogs. It is from 60 to loofj. long by 50 to 

 70 , broad, and has a peristome at its anterior end which becomes 

 narrow as it passes backward. It has an anus. The ectosarc and the 

 endorsarc are distinctly marked. These parasites cause an affection 

 similar to dysentery and may bring about a fatal termination. It is 

 almost impossible to escape noticing the actively moving bodies if a 

 fecal examination is made. When encysted they are round. 



Another ciliate, the Nyctotherus faba, has a kidney -shaped body 

 and is about 25 by 15;*. It has a large contractile vacuole at the 

 posterior end. It has a large nucleus in the center with a small fusi- 

 form micronucleus lying close to it. It has only been reported once for 

 man. 



SPOROZOA. 



This class of protozoa gets its name from the method of reproduc- 

 tion sporulation. These parasites rarely show binary fission. 

 While the sporozoa are found within cells, in the tissues and in 

 internal cavities, as intestine and bile ducts, yet it is as inhabitants of 

 the blood that they have their greatest importance for man these are 

 known as Haemosporidia. A sporozoon may be either naked or 

 amoeboid or be covered with a distinct cuticle. 



Coccidiaria. 



The parasites of the order Coccidiaria are almost exclusively found 

 in the intestines and in the organs connected with it. In the vegetative 



