112 H. L. RATCLIFFE. 



(Figs. 2, 3, 4). The intranuclear bodies bud off masses which 

 pass through the nuclear membrane to the base of the reservoir 

 where they become the blepharoplasts of the daughter organism. 

 New axial filaments (Fig. 4) grow out from these to unite with 

 the original ones (Fig. 5), and the flagellum splits longitudinally, 

 thus forming the new flagella. The connections between the 

 nuclei and the blepharoplast persist long after division is com- 

 pleted (Fig. 14) in fact they apparently persist throughout the 

 vegetative stage. 



The chromatin threads shorten and thicken (Figs. 2-5) until the 

 chromosomes become homogeneous bodies no longer granular in 

 appearance (Fig. 6). The chromosome pairs are never arranged 

 in a typical equatorial plate as is characteristic of mitosis of higher 

 forms. The vacuole within the endosome disappears (Fig. 2-4). 

 Then the endosome elongates at right angles to the long axis of 

 the body (Fig. 4-6). 



3. Metaphase. The chromosome pairs, which, for the most 

 part, lie in planes parallel to the endosome (Fig. 7), begin separa- 

 tion and many forms show the typical V-shapes with the ends of 

 the V more or less closely joined, characteristic of this stage of 

 mitosis in some higher forms. The endosome continues elonga- 

 tion and appears to be fragmented into two or more pieces which 

 lie somewhat twisted about each other (Figs. 6, 7). 



4. Anaphase. The chromosome pairs separate and move to op- 

 posite poles of the nucleus (Fig. 8). As this takes place the 

 individual chromosomes undergo a longitudinal fission and resolve 

 into the rows of paired granules in which condition they pass the 

 remainder of the life cycle. This anaphasic division of the 

 chromosomes accounts for the paired condition seen in other stages 

 of the life cycle. The nuclear membrane constricts closely fol- 

 lowing the movement of the chromosomes to the poles of the 

 nucleus (Fig. 8). 



5. Telophase. Nuclear division is completed with the final 

 constriction of the endosome and the nuclear membrane (Figs. 

 9, 10). The endosome rounds up in the center of the mass of 

 chromosomes which change very little appearance during this 

 stage. Following the constriction of the nuclear membrane there 

 is an invagination of the base of the reservoir which continues 



