TRICHOMONAD FLAGELLATES. 335 



the somatella. In Figure G is outlined the history of one such multi- 

 nucleate somatella in its later phases, with from five to one nucleus. 



Plasmotomy in this case was prolonged for five hours. The first 

 three merozoites were detached rather quickly in succession in less 

 than ten minutes and the subsequent detachments are outlined in 

 figure G. A merozoite with its undulating membrane at the margin 

 of the mass is in an advantageous position for release and by its 

 turning, twisting, and rotating movements gradually increases the 

 outward projection of blepharoplast and flagella until the undulating 

 membrane is in such a position (Fig. G, 2) that its movements drive 

 the merozoite farther and farther out from the common mass, spinning 

 out behind it around the axostyle a thinning thread of cytoplasm or 

 plasmadesmose (Fig. G, 3) which finally parts with a jerk. The pro- 

 jection rounds into the common mass on the one hand and retreats 

 upon the tip of the axostyle on the other as the merozoite swims away. 

 This process is again repeated by another merozoite and another 

 (Fig. G, 3-5) until finally only two remain and these soon detach 

 themselves (Fig. G, 6-8) from one another. The connecting cyto- 

 plasmic threads spun out between the parent and daughter mass are 

 sometimes (Fig. G, 5) twice the normal length of the trophozoite. 

 They bear evidence to the tenacity and viscosity of the cytoplasm at 

 this stage. 



It is obvious that the formative period of the plasmodium offers 

 only 2-4-8-nucleate stages while the prolonged disintegrative period 

 affords all stages with from eight to one nucleus. Some at least, and 

 possibly all of these disintegrative stages may be distinguished from 

 the corresponding ones of the formative period and from the final 

 phase of binary fission by two structural characters. The first of 

 these is the tendency of the chromatin to be massed in an unusually 

 large central karyosome (PI. 4, Fig. 42) and the second, the larger 

 cytoplasmic chromidia (PI. 4, Fig. 45). These distinctions are quickly 

 lost by the freed merozoite. Multiple fission does not seem to give 

 rise to individuals distinguishable from those produced by binary 

 fission. The products of a single merogony are subequal, though 

 occasionally considerable inequalities are seen. We are as yet unable 

 to relate the process of multiple mitosis to gametogenesis or to syn- 

 gamy. 



