638 .MUJiFEL ROBKIJTSON AN1> K. A. MIXCHIX. 



centredosmose. These three figures also sliow three diiferent conditions 

 of the nucleus preparatory to mitosis. In fig. 7 the karyosonie is very 

 distinct, while tlie remainder of the chromatin is pale, but beginning to 

 aggregate into larger masses. In fig. IS the karyosonie is also distinct, 

 but the rest of the chronuitin is darker and the coarse granulation is 

 more distinct. Fig. 9 shows the stage which appears to correspond 

 to the spireme-stage ; the chromatin is in darkly staining masses 

 (chromosomes), connected by fainter lines, and no karyosonie can be 

 made out. All three cells are from the same slide. 



Fig. 10. — Blepharoplast divided, remnant of flagellum still present; 

 nucleus not showing any preparation for mitosis. Cell cut somewhat 

 obliqxiely. 



Fig. 11. — Blepharoplast divided, flagelhuii entirely absent; nucleus 

 as in last. 



Fig. 12. — Blepharoplast and flagellum as in last; nucleus showing 

 beginning chromosome-formation, but karyosonie still distinct. 



Fig. 13.— Cell cut obliquely, showing two blepharoplasts connected 

 by a centrodesmose. 



Fig. 14. — Cell showing the flagellum completely withdrawn, and 

 represented only by a little upgrowth from the liody of the cell ; the 

 two blepharoplasts (centrosomes) have placed themselves on opposite 

 sides of the nucleus, which is still in a very early stage of j)reparation 

 for mitosis, with distinct kaiyosome and pale chromatin. 



Fig. 15.- — Similar stage, luit with the chromatin of the nucleus com- 

 pletely ln'oken up into chromosomes. No karyosonie is to be made out. 

 One centrosome is seen on the right at the side of the nucleus, the 

 other on the left, rather low down and almost under the nucleus. 



Figs. It), 17. — Stages showing the formation of the nuclear spindle. 

 In fig. 16 the chromosomes are still irregular in ariangement, while in 

 fig. 17 they are arranged to form a definite equatorial plate. No 

 flagella have as yet grown out from the centrosomes. 



Figs. 18-21. — Stages with the nuclear spindle and with daughter- 

 flagella growing out from the centrosomes (blepharoplasts). In fig. 

 18 the Fpindle lies slightly obliquely, and only one daughter-flagellum 

 is seen. In fig. 21 the cell is cut obliquely. 



Fig. 22. — Nuclear spindle cut in the plane of the equatorial plate, 

 which is seen from one of its flat surfaces. 



Figs. 23, 24. — Diaster-stages. Fig. 23 shows a cell cut obliquely, and 

 only one of the daughter-flagella is seen. In fig. 24 the nuclear spindle 

 lies obliquely, and only the left-hand centrosome and daughter-flagellum 

 can be seen. 



