120 INTESTINAL FLAGELLATES AND CILIATES 



instead of three have been described but they are not so common 

 and there seems to be room for doubt as to whether these may not 

 be abnormal forms or division stages of the one species. Goodey 

 describes the mouth form of the parasite as having four fiagella. 



Trichomonas swims by active lashing movements of the free 

 fiagella and by wave motions of the undulating membrane. 

 The body revolves as the animal wends its way through the 

 semi-liquid substances in which it lives. Multiplication is by 

 longitudinal division of the body, the fiagella and undulating 

 membranes and internal structures all being duplicated before 

 the animal splits into two. A process of multiple fission resulting 

 in the formation of eight individuals has also been described. 



Encystment, such as occurs in other intestinal protozoans, 

 has definitely been observed only recently in Trichomonas. 

 Some of the flagellates, after escaping from the body with the 

 faeces, soon degenerate, gradually losing all their appendages 



except the undulating membrane. With- 

 out their fiagella, and with their ameboid 

 movements, these animals closely resemble 

 amebae but can usually be identified by the 

 undulating movement which persists at one 

 side of the body.* Others, without losing 



Fig. 31. Trichomonas ,1 • 1 1 j j 



intestinaiis: A, pre-encyst- ^^cir appendages, becomc round and mo- 

 ment stage; B, encysted tioiiless as if in a cyst, but with no cyst 

 Lynch.) ^ " ' ^ ^^ wall around them. When warmed up 



they stretch themselves out and resume 

 an active life. It is probable that these forms are preparing for 

 encystment, since they correspond with pre-encystment forms 

 (Fig. 31 A) recently described by Lynch. Lynch, who found con- 

 siderable numbers of cysts in a heavily infected case in South 

 Carolina, describes the cysts (Fig. 31 B) as thin-shelled, pear- 

 shaped bodies, about three-fourths the size of the active flagellates. 

 The oval body of the animal with its appendages can be seen 

 clearly through the cyst wall in properly prepared microscopic 

 slides. Apparently no multiplication takes place in the cysts, 

 and they are merely " resistance cysts " to enable the animal to 

 withstand unfavorable conditions. Lynch has succeeded in culti- 

 vating Trichomonas and in infecting rabbits with it, but he could 

 not keep specimens alive in water or faeces for more than a few 

 (lavs under the most favorable conditions. 



I 



