FEEDING REACTIONS IN DILEPTUS GIGAS. 



137 



d. .Effect of Trichocysts on Spirostomum. 



When a spirostomum is attacked by a dileptus it contracts vigor- 

 ously as soon as "stung" (Fig. 6, A, B}. This usually produces 

 a violent reaction which serves to get it out of reach of the dileptus 



FIG. 6. Sketches illustrating the effect of trichocysts of Dileptus on Spiros- 

 tomum. A-G, successive stages in process of feeding. When dileptus (d) 

 comes in contact with spirostomum O) as in A, the latter contracts vigorously 

 and remains momentarily motionless (B). Cytolysis begins at area of contact 

 (m) and as the spirostomum reacts negatively, swimming rapidly away, the 

 cytolytic process continues, as in D, ,.and F. Meanwhile dileptus has en- 

 gulfed one or more masses of the disintegrating spirostomum (n) as shown in 

 D-G. 



