92 Uiiirersity of California Publications in Zoology [Vol.16 



Each chromosome is connected with the blepharoplast by a slender 

 fibril (pi. 12. fig:. 9). apparently the remains of a central spindle. 

 These fibrils later disappear and the chromatin becomes distributed in 

 the usual manner of the resting nucleus of the trophozoite (pi. 12, 

 fig. 11). 



The final division of the protoplasm does not take place immedi- 

 ately upon completion of nuclear division, as binucleated forms are 

 generally quite abundant in those preparations in which division is 

 found to occur. 



^luLTiPLE Fission 



In addition to the proces.s of .simple binary fission described above 

 multiple fission also takes place. "What relation this process has to the 

 complete life cycle can only be con.jectured and its solution must await 

 further investigation. 



The process of multiple fission (pi. 12, figs. 12-16) takes place with- 

 out the indi'S'idual becoming encysted. Whether or not it is preceded 

 by conjugation has yet to be determined. Multiple fi.ssion consists 

 essentially of repeated divisions of the nucleus and its associated motor 

 apparatus, by the process already outlined for simple binary fis,sion 

 (pi. 12, fig. 12), but without the synchronous division of the cytoplasm, 

 and followed by disintegrative plasmotomy. Division takes place three 

 times, resulting in an organism or somatella containing eight nuclei 

 and their attendant motor organelles (pi. 12, fig. 13). This somatella 

 is globular in shape and moves with a rolling motion in no constant 

 direction, owing to the incessant lashing of the forty-eight flagella on 

 all sides. 



Plasmotomy or division of the somatella into single in<lividual.s 

 takes place with comparative slowness, one individual being budded 

 off at a time, resulting successively in 7-, 6-. 5-, 4- (pi. 12, figs. 14, 15), 

 3- (pi. 12, fig. 16), and 2-cell (pi. 12. fig. 17) stages. Active locomotion 

 continues throughout this disintegrative phase of the somatella. 



The question might be raised as to the pos.sibility of Trichomitus 

 parvus being only a developmental form of Trichomonas. So far there 

 has been no evidence brought forth to show that Trichomonas passes 

 through a developmental cycle which includes .so great a difference of 

 structure as exists between these two forms. On the other hand, evi- 

 dence seems to point to the fact that Trichomitus passes through a 

 cycle, including binary and multiple fission comparable to that already 

 described for Trichomonas. This fact, in itself, would not preclude 



