290 KOFOID AND SWEZY. 



parabasal bodies of other parasitic flagellates, on the occurrence of 

 chromosomes and of chromosome differentiation in some of the lower 

 Protozoa, and on the simplest type of multinuclear aggregates which 

 foreshadow the organization of the Metazoan type. 



Material. 



The material upon which these observations are based was obtained 

 by the examination of more than 330 individual vertebrate hosts, 

 including, as listed below, ten species of amphibians, three of reptiles, 

 and two of mammals. Nearly every one of the hosts was parasitized 

 by one or more of the species of trichomonads here discussed or by 

 other flagellates. The host species examined were: Amhlystoma 

 tigrinum Green, Diemyctylus torosus Eschscholtz, Aneides lugubris 

 (Hallowell), Batrachoseps attenuaius Eschscholtz, Plethodon oregoncnsis 

 Girard, Rana boylei Baird (adult and larvae), Rana pipicns Kalm 

 (from dealers in Chicago), Rana draytoni Baird and Girard, Rana 

 cateshiana Shaw (from Honolulu, H. I.), Hyla regilla Baird and Girard, 

 Bvfo halophilus Baird and Girard, Pituophis catcnifer Baird and 

 Girard, Python rcticulatus (Schneid.) (from Borneo), Crotalus ore- 

 gonus Holbrook (from Guerne\ille and Patterson, California), Pcro- 

 myscus maniculatus gambeli Baird, and albino mice (Mus sp.) from the 

 culture stock of Professor J. A. Long. They were, unless otherwise 

 stated, all obtained in Berkeley, or in the Coast Range of mountains 

 within thirty miles of San Francisco from Saratoga on the south to 

 Inverness on the north. 



Technique. 



As has been pointed out by Martin and Robertson (1911), the 

 division forms are seldom found outside the mucous lining of the 

 intestine, though the usual vegetative forms are numerous in the 

 lumen and in the intestinal contents. Scarcity of division forms in 

 most smears is probably due to the length of time between recurring 

 division cycles, though a very few dividing forms may be found in 

 nearly every host examined. Some smears have always been made 

 from the intestinal contents, but, for the most part, they have been 

 made from the wall itself, a small fragment of the wall being smeared 

 over the cover-glass, which was then placed in the fixative. In 

 every case moist film preparations were made, dried smears having 



