340 KOFOID AND SWEZY. 



Kuczynski (1914) finds that the old axostyle disappears and that 

 new ones grow out, just how is not clear. We find no indi\aduals 

 in late telophase without one (Fig. 59) or two (Fig. 61) axostyles. 



Plasmotomy is delayed some time after the completion of the full 

 complement of new extranuclear organelles, the organism remaining 

 in the state of an active, highly amoeboid, binucleated plasmodium, 

 as in T. augusta. 



Multiple mitosis in Trichomonas muris. 



This phase of the life-history has escaped the notice of Kuczynski 

 (1914) in this species also, as well as in the closely related T. camae. 

 It occurs in certain hosts which we have examined and not in others. 

 Our series of the stages (PI. 5, Figs. 62-66) is confined wholly to the 

 disintegrative phase of the plasmodium or somatella. 



We find no indications of more than eight nuclei in plasmodia but 

 have not seen the last two pervading mitoses which result in its 

 formation. Our disintegrative series is limited to plasmodia with 6 

 (PI. 5, Fig. 62), 5 (Fig. 63), 4 (Fig. 64), 3 (Fig. 65), and 2 (Fig. 66) 

 nuclei respectively. Some of the earlier phases (Figs. 62, 64), as in 

 T. augusta, have their nuclei filled with a dark intranuclear chromidial 

 cloud and in the later ones (Figs. Go, 66) the chromatin becomes segre- 

 gated in a few large karyosomes. The plasmodia, as in T. augusta, 

 disintegrate by the progressive detachment of the small merozoites 

 one by one from the common mass. 



The prolonged coherence of the two daughter cells after nuclear 

 division is completed, thus forming temporarily a binucleate organism 

 with two axostyles and eight flagella is significant of the probable 

 method of evolution of the Hexamitidae, for both Hexamitus ( = Octo- 

 mitus) and Lamblia have approximately the equipment of organelles 

 which such a temporary binucleate plasmodium of the Tetramitidae 

 presents. This temporary phase of the trichomonad becomes the 

 permanent one of the higher group. 



Tetratrichomonas prowazeki AlexeiefF. 



Plate 6, Figures 67-78. 



First described by Alexeieff (1909b, 1910) as Trichomonas prowazeki 

 and later assigned by Parisi (1910) to the subgenus Tetratrichomonas, 

 which in the following year was raised to generic status by Alexeieff 



