SPECIAL MORPHOLOGY OF THE PROTOZOAN NUCLEUS 267 



Fig. 141, E, F). Thus the chromosomes, as in the higher types, are 

 brought in contact with the central-spindle fibres. They then split 

 longitudinally, and through the agency of mantle-fibres are separated 

 into two equal groups, each group drawn toward its own daughter- 

 sphere. Within the sphere the fibres are focussed in a centrosome, 



t . 





'$ V 





cK^St 



B 



Fig. 141. Mitosis in Noctiluca miliaris. 

 s, sphere; c, centrosome ; ch, chromosomes. 



which, at this period, can be demonstrated with the greatest ease. 

 The division is finally completed by the separation of the remainder 

 of the nucleus and the re-formation of the daughter-nuclei, while the 

 chromosomes disintegrate into granules, which again form the large 

 chromatin reservoirs characteristic of Noctiluca (Fig. 134, E). 



As Ishikawa ('94) first pointed out, the centrosome within the 

 sphere, the mantle-fibres and their insertion in the chromosomes, 



