MITOSIS 105 



daughter chromosomes, and finally enter the daughter nuclei. Bodies 

 of this kind have been described by Reichenow (1921) in Karyolysus, and 

 the writer has seen them in Hepatozoovi baJfouri (Fig. 35). These plastin 

 bodies are not essentially different from karyosomes, which consist mainly 



% 



•!» 



<^*. 



'9 





Fig. 61. — Amgeboid Phase of Dimastigamceha gruberi from Culture on Agar 

 Plate showing Method of Nuclear Division ( x ca. 1,350). (Original.) 



1. Usual type of amoeba. 



2. Commencing nuclear division. The karyosome has become elongate and granular. 



3. The karyosome has become dumb-bell-shaped and the nucleus is filled with granules. 



•4. There is an equatorial plate of dividing chromosomes, and the dividing karyosome has formed 

 the pole caps, which are still united by a fibre (centrodesmose). 



5. The daughter chromosomes have become aggregated, and are passing towards the pole caps, 



which have lost the connecting fibre. Each pole cajj has a central granule. 



6. The nucleus has divided and each half is retracting. 



7. Slightly later stage witli tlaughtcr nuclei still further retracted. 



8. Form with two reconstituted nuclei. 



9. Form with two nuclei in division: equatorial plate stage. 



10. Form with two nuclei in different stages of division. 



of achromatic material. In nuclear division the plastin substance, 

 whether it be regarded as a karyosome or not, may divide into two parts, 

 one of which goes to each daughter nucleus, as in Dimastigamoeba (Fig. 61), 

 or it may break up and disappear as a single body, to re-form in the 

 daughter nuclei, as in HartmanneUa (Fig. 56). 



