INTESTINAL FLAGELLATES OF RATS 131 



trichomonads, although Kofoid and Swezy (1920) consider the 

 parastyle to be homologous to one of the axostyles of Giardia. 

 Grasse (1926) believes the parastyle to be an axostyle arrested in 

 development, but does not regard the so-called axostyles of Giardia 

 and Hcxamitus as true axostyles, but as thickened and chromatic 

 intracytoplasmic portions of the posterior flagella. 



As to function, the axostyles have been regarded by many as 

 primarily skeletal {e.g., Wenyon, 1907), or as an organ of 

 fixation {e.g., Kuczynski, 1914), or as locomotor and the equiva- 

 lent of an intracytoplasmic flagellum {e.g., Kofoid and Swezy, 

 1915). Generalizations regarding the homologies and functions 

 of all the structures that have been termed axostyles are probably 

 unwarranted, each kind needing its own interpretation. 



The cJiromatic basal rod is a chromophyllic rod at the base of 

 the undulating membrane. It varies in length, thickness and shape 

 in different species and may be replaced by a row of chromatic 

 granules (T. pan'a). It is absent from the Trichomastix group 

 of trichomonads. Grasse (1926) states that it is not composed of 

 chromatin, although it stains heavily with hematoxylin. It is 

 usually regarded as having some function relating to the activities 

 of the undulating membrane, but its physiology has not been 

 fully studied. In Chiloniastix the parabasal of Kofoid and Swezy 

 (1920) may be homologous to the chromatic basal rod of tri- 

 chomonads, as may also the chromatic peristomal fibers of Giardia. 



Chromatic granules in various groupings are common in 

 trichomonad flagellates. More frequently there are one or more 

 rows just beneath the chromatic basal rod and a row or group 

 along the axis of the body, beginning at the blepharoplast. These 

 are well developed in T. muris, less so in T. miniifa. The more 

 peripheral group appears to be absent in P entatrichomonas and 

 Hexamastix, but in the former there is a chromatic streak on the 

 ventral side of the axostyle just back of the blepharoplast. In 

 T. parz'a the chromatic granules are crowded into the anterior 

 third of the body, usually with no definite arrangement except a 

 row under the undulating membrane. The significance of these 

 granules is quite obscure, but the axial group attached to the 

 blepharoplast may constitute the material which aids in the genera- 

 tion of new axostyles during fission after the parental axostyle has 

 degenerated. In some species {P entatrichomonas, Fig. 12, f.) the 

 anterior part of the body may stain more heavily than other por- 



