628 



FERTILIZATION 



fuse to form about eighty dumb-bells. Since the diploid chromosome num- 

 ber is forty in this species, four granules (two dumb-bells) evidently 

 represent a chromosome, just as they do in E. patella, and forty dumb- 

 bells pass to each pole in the anaphase. 



In Kidderia {Concho phthmus) mytili, Kidder (1933a) found thirty- 



Figure 148. Stages in the first maturation division of Euplotes patella. A, early nucleus 

 with finely granular chromatin; B, chromatin reticulum condensing in center; C, para- 

 chute stage; D, later parachute showing chromatin granules migrating from upper pole, 

 endobasal bodies and intradesmose visible; E, metaphase stage with thirty-two chromo- 

 meres arranged in eight chromosome groups; F, anaphase stage with sixteen chromo- 

 meres (eight chromosomes) passing to each pole. (Turner, 1930.) 



two granules forming on the spindle and sixteen passing to each pole, 

 as in E. patella. Sixteen is the diploid number in this species, so the 

 thirty-two granules represent half a chromosome each, although there 

 is no visible association between the halves. 



Gregory (1923) described forty-eight chromomeres appearing in the 

 prophase and fusing to form twenty-four dumb-bell chromosomes in 

 Oxytricha fallax. In this case twelve dumb-bells pass to each pole. If 



