5^2 RESEARCH IN PROTOZOOLOGY 



The work of Cropper and Drew (1914), using various "auxetics" 

 and "kinetics" to produce encystation and excystation in free- 

 living amcebae, seems to ofifer many helpful suggestions in study- 

 ing the cysts of the various protozoa and in the production of 

 cysts in those organisms in which cysts are unknown, either in 

 culture or in their natural habitat. This same work calls to mind 

 many problems in the rate of multiplication, and length of life or 

 organisms in culture. In the cultivation of an amoeba from the 

 turtle, Barret and Smith (1924), cultures which had almost com- 

 pletely died out after two years on artificial media were "rejuven- 

 ated" by the addition of 0.2% of choline and carried for several 

 months longer. 



(5) The effects of various chemicals and dyes on protozoa in 

 vitro and in vivo. On the parasitic amoebse, emetine and various 

 other drugs have been found to exert a more or less specific efifect, 

 when administered in cases of amoebic infection. No specific drug 

 has been found for infections with the flagellated or ciliated 

 PROTOZOA. The treatment of infections with this class of organisms 

 offers one of the biggest fields for research at the present time. 

 Numerous aniline dyes, as well as various drugs, should be studied 

 for their effects upon protozoa, both in the test tube and in the 

 living organism. 



{6) A study of the specificity of protozoa for their original 

 host, and for their original habitat in a given host. Hegner (1928) 

 has done some valuable work on this problem. When we consider 

 the universal prevalence of Trichomonas and other intestinal pro- 

 tozoa and the great variety of animals infected by these organisms, 

 a vast amount of work could be done to determine whether or not 

 these organisms are specific for the animals and for the organs in 

 which they are found. The mutations in bacterial life taking place 

 in changed environment and in different hosts are wellrknown. 

 Might we not find like changes taking place in protozoa, under 

 changed conditions of life? This would seem a broad field for 

 future investigation. 



