460 University of California PuMicaiions in Zoology [Vol. 20 



After the separation of the two daughter nuclei in the early 

 telophase, binary fission is carried to completion and two daughter 

 flagellates are formed. The flagellates appear to swim about actively 

 throughout the whole process of mitosis. Since cysts could not 

 be identified, there is no evidence for division during encystment, 

 although it is quite possible that, as in Euglcna (Tschenzolt', 1916; 

 Zumstein, 1899), such a process may occur. 



DISCUSSION 



As Hartmann and Chagas (1910) have suggested, the euglenoid 

 nucleus is probably more easily studied than that of any other group 

 of flagellates; yet the literature contains very few good accounts 

 such as that of Tschenzoff (1916), for example, and the different 

 authors hold conflicting viewpoints with regard to the structure of 

 the nucleus and the nature of nuclear division. Mitosis of one sort 

 or another has been described by Klebs (1892), Blochmann (1894), 

 Keuten (1895), Dangeard (1902), Prowazek (1903), Berliner (1909), 

 Hartmann and Chagas (1910), Haase (1910), Belaf (1916), Tschen- 

 zoff (1916), Sehiis.sler (1917), Dehorne (1920), and Gard (1920). 



Amitosis has been described in a few forms, for example, Eutreptia 

 (Steuer, 1904) and Copromonas [Scytomonas?] (Dobell, 1908). As 

 for Copromonas, Berliner (1909) finds chromosome formation in well 

 stained preparations of Copromonas major; also, Schlissler (1917) 

 describes in Scytomonas chromosome formation in properly destained 

 haematoxylin preparations, and states that an appearance of amitosis 

 is seen in overstained preparations ; however, these chromosomes were 

 interpreted by Schiissler as being in the karyosome. Hence, it is ([uite 

 possible that Dobell 's account of amitosis in Copromonas suhtilis is 

 the result of inadequate staining techniqiie. Dobell (Dobell and 

 O'Connor, 1921) has recently modified his original designation of 

 nuclear division in this form to "amitosis or a simple form of 

 mitosis. ' ' 



Sexual phenomena have been described in a few instances (Weisse, 

 1856; Dobell, 1908; Berliner, 1909; Haase, 1910), but such descrip- 

 tions do not rest upon critical cytological evidence and are not to 

 be accepted without confirmation. In Copromonas, Dobell asserts 

 that two flagellates become fused at their anterior ends, the union 



