128 D. H. WENRICH 



As has been observed by other authors, the undulating mem- 

 brane seems occasionally to be broken, allowing the entire 

 flagellum to become free. Individuals with the posterior flagel- 

 lum free are not rare in fixed and stained preparations (fig. 15). 



The chromatic basal rod takes origin in the blepharoplast, 

 or possibly the posterior portion of it, and extends along the 

 surface of the body at the base of the undulating membrane. 

 It, together with the undulating membrane, takes a spiral course 

 on the living animals, as in figures 5 and 17, as previously noted, 

 passing posteriorly from the left over to the right. It ends free 

 in the cytoplasm. It appears to be a body of some rigidity 

 because changes in its position are usually accompanied by corre- 

 sponding changes in the form of the body. As described by 

 Wenyon ('07), it may project from the body as a stiff thread. 

 It is broadest near the middle, tapering to a slender distal ter- 

 minus, and to a less slender proximal or anterior end attached 

 to the blepharoplast. Near the anterior end it often exhibits 

 a bend, which may even be S-shaped, which suggests a high 

 degree of flexibility of that region (fig. 14, e.g.). 



Most observers have represented this structure as a homo- 

 geneous rod. In this species I have been considerably puzzled 

 about its organization, for frequently it appears to have em- 

 bedded within it a row of granules on the inner side, similar to 

 the row which lies close to it, but deeper in the cytoplasm (figs. 

 11 and 14). At other times the additional row seems to be just 

 in contact with the rod (figs. 2, 10, 13, 21), and again the row 

 may be adjacent to but not in contact with the rod (fig. 8). 

 These observations indicate that new rows of granules take their 

 origin from the basal rod and migrate inward, possibly replacing, 

 during division, the one that is always found close to and parallel 

 with the rod. 



This outer row of chromatic granules close to the chromatic 

 basal rod is very characteristic of this species and extends from 

 60 per cent to 90 per cent of the length of the rod out from the 

 blepharoplast. It is figured by Hartmann ('10), Wenyon ('07), 

 Kuczynski ('14, '18), and Kofoid and Swezy ('15). Another 

 row of similar granules is found deeper in the cytoplasm, and 



