490 J. A. DAWSON 



after the first Oxytricha has been swallowed, it is a much more 

 simple process to swallow others, since the peristome then is 

 considerably distended (figs. 9, 11, 13, and 16), and accordingly 

 the process goes on rapidly until the cannibal is literally gorged 

 with the bodies of its relatives (fig. 15). 



2. Digestion of the ingested animals 



For the purpose of studying the time necessary for the diges- 

 tion of the ingested animals, thirteen cannibals were isolated 

 from culture 2 B (p. 494) at 8 a.m., December 31st. All had 

 become cannibals since 1 a.m. of the same day, i.e., at approxi- 

 mately the same time. In these cannibals the bodies of the 

 ingested animals could be plainly seen and an accurate count 

 made by using a binocular microscope with a lens combination 

 giving a magnification of about 50 diameters. Of the thirteen 

 animals thus isolated, 3 contained 3 bodies each; 5, 4 bodies 

 each; 2, 5 bodies each; 1, 6 bodies; 1, 7 bodies, and 1 had 8 

 bodies. Observations were made on these animals for the next 

 fifteen hours and specimens were stained from time to time until 

 a fairly complete series illustrating the whole process of diges- 

 tion was obtained. A series of measurements was also made 

 during the experiment which shows that the oft'spring of the can- 

 nibals are only slightly above normal size at the end of the 

 second generation. 



Cannibals containing three bodies. No. 1. At the end of 2 

 hours the three food vacuoles containing the ingested animals 

 were still distinctly seen. At the end of 3 hours no trace of 

 any of the bodies could be seen, although the animal was still 

 distinctly larger than normal (120 x 51 //). It was then stained. 

 The stained preparation showed remains of one body with the 

 macronuclei still present, but stained very faintly. 



No. 2. Little change in the appearance of the bodies was 

 noted during the first 2 hours. Gradual disappearance of the 

 outlines of these was noted during the next hour, at the end of 

 which the animal was fixed and stained. The preparation 

 showed the presence of two large vacuoles faintly stained, one 



