245] STUDIES ON GREGARINES— WATSON 35 



in rotation set in motion currents in the surrounding medium and slowly 

 attract into this ever-widening circle of influence particles of debris or 

 nearby gregarines. If debris is drawn into the whirlpool, it is not re- 

 tained, but slips to the outside again. Another gregarine is, however, 

 attracted and held probably because of the mucus on its exterior, and 

 caused to rotate with the first one. If two gregarines are attracted, the 

 force exerted by the first is too weak to hold both and one is invariably 

 liberated. A sporont is apparently unable to make a cyst alone. A sin- 

 gle sporont has been seen to rotate for three hours without succeeding 

 in attracting another and then to straighten out suddenly and move to 

 another part of the field. 



When such an association is formed, the sporonts are not attached 

 by particular parts of the body, as are associations of the genus Grega- 

 rina, but are held together in a haphazard fashion by secretions only. In 

 rotation the sporonts come closer and closer together laterally, slipping 

 by a few sudden jerks until one does not project beyond the other, the 

 protomerites bend around so as to meet the posterior ends of the deuto- 

 merites (Figs. 234 to 236), the deutomerites projecting and contracting so 

 as to leave no unfilled interstices until the result is a compact sphere. In 

 one such process, there was formed in the middle of one side of each 

 deutomerite a tiny cupped indentation and the two cups fitted together 

 to form a perfect sphere. This sphere became smaller and smaller as 

 the cyst developed and finally disappeared in the general breaking down 

 of the inclosed sporont walls (Figs. 235, 238). 



The mass continues its slow rotation for hours. After a compact 

 mass has been formed one can still distinguish the nuclei and the proto- 

 merite and deutomerite of each sporont, the former by the pale tan color 

 (Figs. 239, 240). This demarcation is lost and soon after the faintly vis- 

 ible lighter nuclear areas disappear. The straight line which separates 

 the two sporonts (their lateral walls) remains visible for twenty-four 

 hours after the cyst has begun to form. It disappears finally and the 

 cyst-raa«;s becomes perfectly homogeneous throughout (Fig. 241). 



All the time the mass is revolving there is being exuded from the 

 two bodies the sticky, gelatinous, transparent secretion. This exudation 

 follows the animals as very slender spiral threads and forms a spirally 

 arranged layer constantly increasing in width as rotation continues. 

 When rotation ceases there is formed around the cyst-mass an apprecia- 

 ble layer of this gelatinous matter arranged as very fine concentric 

 threads. 



Motion of the mass was watched in one instance to completion. My 

 notes opposite the time of each successive complete rotation read as fol- 

 lows: "Brings another gregarine into the vortex; the two rotate to- 

 gether; shoves a third gregarine out of the way; retracts same; the two 



