22O J. MCA. KATER. 



cylindrical shape of the nucleus comes an enlargement of the 

 basal granules, preparatory to their division which will take place 

 just before constriction of the nucleus is complete. At this time 

 the chromatin is clumped into a single mass. The two basal 

 granules divide to form four, each of which gets one of the old 

 flagella. Although no unquestionable figures were found which 

 showed the outgrowth of new flagella it is presumed that this is 

 the method of formation, because if the old flagella split we would 

 expect that to happen at the same time that the basal granules 

 divide and that is not the case. The duplication is by outgrowth 

 in P. agiles (Doflein, 1916), Dunaliella (Teodoresco, 1905), 

 Stephana pter a (Dangeard, 1910), all belonging to this same 

 family. 



The history of the chromatin from the beginning of the telo- 

 phase, when there are single masses at the poles, until the con- 

 struction of the daughter nuclei is complete is a rapid return 

 through the same stages in reverse order that were passed through 

 in the prophase. The solid masses break up to form a spireme 

 which goes back through the quadri- and bi-partite karyosome to 

 the single condition with which we started. By the time the 

 quadri-partite condition of the karyosome is reached the cell 

 shows marked furrows on both the anterior and posterior ends. 

 In most flagellates fission has been described as beginning at one 

 or the other end. The present case is an example of equal 

 furrowing all around the cell-body. The resting condition is 

 reached by the nuclei, or is very closely approximated, by the 

 time fission is complete. It is interesting to note that the two 

 daughter nuclei are frequently not advanced to the same degree. 



We must now return to the first elongation of the nucleus and 

 find what happens to the area of dense cytoplasm which surrounds 

 the nucleus. A glance at the figures from metaphase on will show 

 that there is a fairly even distribution of this material to the 

 daughters. Sometimes it surrounds the nucleus in an even layer, 

 in others it is almost all on one side, and in rare cases it is slightly 

 drawn away from the nucleus. A band of this substance can be 

 seen stretching between the daughter nuclei just before the cells 

 separate. The chromatic nature of this material probably indi- 

 cates that, although the nuclear membrane remains intact during 



