1915] McCulloch: Critliidia leptocoridis 5 



chromatin bar lying in a transverse position with respect to the long 

 axis of the body. At still another angle the "kinetounelens" may 

 present the appearance of a single round chromatin mass. There is a 

 definite connection between the "kinetoniicleiis" and the basal granule 

 at the base of the flagelhim in the form of numerous fine unstained 

 fibers which form a cone-shaped structure at the base of the flagellum 

 (pi. 2, fig. 54). Chagas (1909, pi. 13, figs. 13-18) figures a similar 

 structure in the crithidial stages of Scliizotrypanum cruzi. Since these 

 fibers do not stain with Giemsa or iron haematoxylin it was some time 

 before the connection was observed. 



At the apex of these fibers there is a very small basal granule (pi. 

 3, figs. 57-62) or a slight enlargement of the base of the flagellum. 

 In many instances it is exceedingly difficult to demon.strate the pres- 

 ence of this structure. 



The rhizoplast is a faint line connecting the " kinetonucleus " with 

 the nucleus. In the vegetative forms this line does not usually pass 

 from the central karyo.sorae of the nucleus to the "kinetonucleus," as 

 seen in plate 2, figure 54. In plate 2, figure 55, the rhizoplast can 

 be traced from the nuclear membrane of the nucleus to the chromatin 

 mass of the "kinetonucleus." There is still another method of at- 

 tachment on the part of the rhizoplast : it may come from the basal 

 granule and pass around the side of the "kinetonucleus" (pi. 3, figs. 

 57, 60). 



An "axostyle" is present in Critliidia leptocoridis apparently in 

 the form of a chromatic thread extending from the basal granule to 

 the posterior end of the body, where it may terminate in a small 

 chromatin granule (pi. 3, figs. 58-59). This "axostyle" is most 

 readily seen in the living flagellates of the vegetative phase. Such 

 stains as Giemsa and iron haematoxylin show it. A certain per cent 

 of the flagellates in the prepared material show an additional structure 

 parallel with the "axostyle" line in the form of an extension of the 

 light or unstained area about the "kinetonucleus" to the posterior end 

 of the body (pi. 4, fig. 75). Mackinnon (1910), Wenyon (1913), and 

 other investigators have described such a structure in Herpetomonas 

 tmiscae domesticae. In Critliidia leptocoridis in a few instances it has 

 the appearance of a "longitudinal canal" outlined on the one side by 

 the "axostyle" thread and on the other by a similar thread, less dis- 

 tinct (pi. 4, fig. 75), which connects with the flagellum. The relation of 

 this "axostyle" to the rhizoplast in this form is not clear. If this 

 be an axostyle, the homology with respect to certain structures in 



