The Chromosome Cycle in Coccidia and Gregarines. 85 



E L K 



Fig. 1. — Chromosomes of Aggregata eberthi. 



The figures are tracings (of chromosomes only) from detailed drawings made with the 

 camera lucida at a magnification of 2500 diameters. The letters a-f (or a'-f) indicate 

 throughout the six chromosomes forming the haploid group, or typical chromosome 

 complex, of Aggregata. The chromosomes are lettered consecutively in order of 

 magnitude — from a (the largest) to /(the smallest). 



A. Nucleus of male — prophase of first division. B. Equatorial plate — first division 

 of male. C. Early anaphase groups at first division in male. D. Chromosome group 

 entering into resting nucleus — end of first (multipolar) division of male. E. Chromo- 

 somes in macrogamete nucleus before fertilization. F. Chromosomes in zygote nucleus 

 — prophase of first division. G. Double (paired) chromosomes on equatorial plate — 

 first spindle of zygote nucleus. H. Early anaphase groups — first spindle of zygote. 

 K. Chromosome group entering into resting nucleus — end of first (multipolar) division 

 of zygote. L. Chromosome group —anaphase of later division (bipolar) of zygote. 

 M. Chromosome group on equatorial plate of second division in spore. 



