CHILOMASTIX IN ANIMALS 627 



month, when it was apparently absent or present in such small numbers 

 as to escape detection. As in other flagellate infections, the number of 

 organisms present is subject to marked periodic fluctuations. The evidence 

 as to pathogenicity is still wanting. The writer (1920) has noted that in 

 sections of the large intestine the flagellates may be found within the 

 lumen of the glands, but could find no indication that invasion of the 

 tissues could take place. Kessel (1924a) reports the successful inoculation 

 of monkeys with C. mesnili. 



The culture of C. mesnili has been successfully carried out by Boeck 

 (1921a), who used a medium consisting of one part of human serum to 

 four parts of Locke's solution, to which 0-25 grain of dextrose had been 

 added. In this medium at 37° C. the flagellates survived and multiplied 

 for eight or nine days till they were overgrown by the bacteria. By sub- 

 culture every two or three days the strain was maintained for about five 

 months. Reichenow (1923) has also cultivated the organism in a medium 

 prepared by dropping dilute serum into hot saline, so that flocculi are 

 formed. He has grown it from stools which were microscopically negative, 

 a fact which demonstrates the value of the culture method for diagnostic 

 purposes. Boeck and Drbohlav (1925), and Thomson, J. G., and Robertson 

 (1925), report the culture of C. mesnili in Boeck's L.E.S. medium. 



The small round forms of C. mesnili, which have a diameter of 3 to 

 6 microns, often have the cytostomal groove obscured (Fig. 256, 7-8). 

 In this condition they resemble the flagellate described as Enteromonas 

 hominis by Fonseca. From an examination of their films, the writer is 

 able to state that the cases of E. hominis infections recorded from the Sudan 

 by Chalmers and Pekkola are in reality ones of C. vnesnili, in which the 

 majority of the fiagellates are in the small rounded form. This fact raises 

 the question as to whether the other cases of E. Jiominis infection are not 

 due to the same organisms. If this be so, the name Enteromonas becomes 

 a synonym of Chilomastix (see p. 307). 



CHILOMASTIX IN ANIMALS. 



Flagellates of this genus are fairly common parasites of animals. 

 Though many of these have been given specific names, it is very doubtful 

 if they can be distinguished from one another. C. mesnili varies so much 

 in size, as also do the cysts, that this feature is of little value in the dif- 

 ferentiation of species. Thus Alexeief! (1914) expressed his belief that the 

 human flagellate, C. mesnili, is identical with C. caulleryi of frogs. 



C. hettencourti Fonseca, 1915, is parasitic in the intestine of rats (Rattus 

 norvegicus). This form has been seen by the writer on several occasions in 

 both rats and mice, and he can find no differences between it and the human 

 form. Fantham (1925) records as C. muris a form in the gerbil {Tatera 



