120 RESEARCH IN PROTOZOOLOGY 



fresh-water crustacean Cyclops, and certain euglena-like forms 

 that occur in the intestine of frog tadpoles and that have been 

 described by Wenrich (1924) as Euglenamorpha Jicgneri and by 

 Brumpt and Lavier (1924) as Hcgneria Icptodactyli. Probably 

 other species occur in the intestine of tadpoles. That cross-infection 

 experiments are possible was demonstrated in the case of Euglena- 

 morpha hegncri by the writer (Hegner, 1923). 



Another group of plant-like flagellates that contains a large 

 number of parasitic species is the order dinoflagellata. Most 

 of these belong to the family blastodinid.^ which has been treated 

 in detail by Chatton (1920), to whose work the reader is referred. 



The animal-like flagellates are to be found in the digestive tract 

 of almost every species of animal and each host as a rule contains 

 many different species. Kofoid, for example, records the results 

 of the examination of five species of amphibia, four species of 

 reptiles and six species of mammals. Every species studied was 

 found to be infected with intestinal flagellates and flagellates were 

 obtained from all but two of the 329 individuals examined. 

 Furthermore, each host species contained a number of species of 

 flagellates. For example, the salamander Diemyctylus torosus was 

 found to harbor fourteen species of flagellates belonging to ten 

 genera. Probably only a small fraction of the intestinal flagellates 

 in existence have been described and named. The order pro- 

 TOMONADIDA contains the majority of the parasitic mastigophora, 

 not only intestinal species but also blood-inhabiting species be- 

 longing to the family trypanosomid^. Certain of the families that 

 contain intestinal species will now be discussed. 



In the family monadid.e is the genus Oikomonas which con- 

 tains not only a number of free-hving species but also species 

 that have been reported from the intestine of man and lower 

 animals. The members of the genus are very small and on that 

 account rather difiicult to study. Resembling Oikomonas some- 

 what is the flagellate known as Histonionas mclcagris which ap- 

 pears to invade the tissues of certain birds and bring about the 

 disease known as blackhead in turkeys and fowls. 



Among other flagellates belonging to the family monadid^ 

 that may probably be obtained without great difficulty and that 

 would well repay study are species belonging to the genus Rhizo- 

 mastix which have been reported from the intestine of amphibia 

 and insect larvae, and species of the genus Hcteromita, among 



