1920] Kofakl-Swezij: Murpholvgy and Mitosis of Chiloviastix 125 



eouut'cted posteriorly to the centrosome on the anterior face of the 

 nuclear membrane by the nuclear rhizoplast (fig. B, nuc. rhiz.) and 

 transversely to the secondary blepharoplast (fig. B, sec. Meph) by the 

 transverse rhizoplast (fig. B, tr. rhiz.). It is somewhat widely sep- 

 arated from the other two blepharoplasts at the anterior end of the 

 cytostome in this stage, and also from tlie nucleus which has migrated 

 postero-laterallj'. Because of its connection with and more intimate 

 relationship to the nucleus, this blepharoplast shovild be regarded as 

 primaiy and the other two as of secondary and tertiary status. 



The right anterior or secondary blepharopla'St (fig. A, sec. bleph.) 

 in the free flagellate (pi. 15, fig. 4) lies close to or appears to be fused 

 with the right posterior or tertiary one in a more or less elongated 

 body. In some cysts not heavily decolorized the two granules can not 

 be differentiated. In some favorably oriented and strongly decolor- 

 ized cysts it is possible to distinguish the secondary {sec. Meph.) from 

 the tertiary blepharoplast {tert. bleph.) and to see the short peri- 

 stomal rhizopla.st connecting the two (pi. 16, fig. 10). The secondary 

 blepharoplast gives rise anteriorly to the single right flagellum which 

 is sliglitlj' detached from the other two (pi. 15, fig. 3), and posteriorly 

 to the straight parastyle which underlies the left rim of the cytostome, 

 and also to the short peristomal rhizoplast which joins this secondary 

 blepharoplast to the tertiary blepharoplast. 



The tertiary blepharoplast (fig. C, ter. bleph.) is at the anterior 

 end of the rim of the cytostome. It gives rise anteriorly to the peri- 

 stomal rhizoplast connecting it with the secondary blepharoplast and 

 posteriorly to the undulating cytostomal flagellum, to the looped peri- 

 stomal fiber (perist. f.) and to the curved parabasal (par. b.) which 

 is attached to and posteriorly underlies the peristomal fiber. It is 

 often obscured by the secondary blepharoplast and bj' the thickened 

 anterior ends of the peristomal fiber. 



The peristomal fiber is a fine thread encircling the so-called 

 cytostome in its immediate rim and originating in the tertiary 

 blepharoplast. Its proximal ends, as they emerge from this granule, 

 are thickened and continue so for 0.25 to 0.33 of the length of the 

 cytostome, while beyond this section it is a delicate fibril which 

 encircles the remainder of the opening. Owing to its location in 

 the immediate surface of the body, and to its overlying the parastyle 

 on the left side and the parabasal on the right, it is easily confused 

 with these structures or overlooked, especially if the stain is not 

 sufficiently decolorized. Furthermore, the varying degrees of contrac- 



