PLATE 1 



EXPLANATION OF FIGURES 



4 A typical normal individual from culture A in the fiftieth generation. 

 July 24, 1917 (dorsal view). 



5 Typical pair from stock of culture A fused in the peristomial regions. 



6 Typical pair from stock of culture A. Appearance closely simulating 

 that of conjugating animals (Del. hem.). 



7 Pathological specimen from stock of culture A in 283rd generation, Novem- 

 ber 6, 1917. Preparation made at the end of the fourteenth day without 

 division. 



8 A typical cannibal with remains of five ingested animals, two of which 

 are in an advanced stage of digestion. A kernspalt is present in each macro- 

 nucleus of the cannibal (dorsal view). 



9 A cannibal which has just ingested an animal, the peristome of which is 

 visible. The posterior macronucleus of the ingested animal is partially obscured 

 by the macronucleus of the larger animal. A large vacuole containing the re- 

 mains of an individual now almost completely digested is at the left of the poste- 

 rior macronucleus of the cannibal (ventral view). 



10 An individual, descendant of a cannibal in the second generation (No. 6, 

 p. 491). 



11 A cannibal which has just ingested a pair of animals which were fused as 

 if conjugating. The peristome is much distended. 



12 An individual, descendant of a cannibal in the first generation, which 

 shows almost complete digestion of ingested animals. The remains of the 

 macronuclei of an ingested animal are visible as two chromatin bodies on the 

 left of the posterior macronucleus (ventral view) (p. 492). 



510 



