REPRODUCTION 



155 



the slight enlargement, and migration toward the centriole, of the 

 nucleus (6). The centriole first divides into two (c, d) and the nucleus 

 becomes located between the two centrioles (e). Presently spindle 

 fibers are formed and the nuclear membrane disappears (/, g). After 



\\«m\ 



ymmmn 



••fin Hi' '».'. ' 



/ f'n 



Fig. 59. Nuclear and cytoplasmic division in Oxnerella maritime/,, X about 

 1000 (Dobell). a, a living individual; b, stained specimen; c-g, prophase; 

 h, metaphase; i, anaphase; j, k, telophase; 1, division completed. 



passing through an equatorial-plate stage, the two groups of 24 

 chromosomes move toward the opposite poles (g-i). As the spindle 

 fibers become indistinct, radiation around the centrioles becomes 

 conspicuous and the two daughter nuclei are completely recon- 

 structed to assume the resting phase (j-l). The mitosis of another 

 heliozoan Acanthocystis aculeata is, according to Schaudinn and 



