AN AMICRONUCLEATE OXYTRICHA 507 



4. While in this state, a) animals fuse in pairs in a manner 

 similar to that of conjugating animals; h) cannibalism takes 

 place. 



5. Animals, fused as described in 4a, either remain fused until 

 death occurs or separate. In the latter case the organisms 

 continue to reproduce and give no signs of being in a depressed 

 condition. 



6. When cannibalism has occurred, digestion of the ingested 

 animals proceeds rapidly and a return to the typical size and 

 structure soon takes place. 



7. Cannibalism has the effect of raising the division rate 

 somewhat for a short time. 



8. This amicronucleate race of Oxytricha hymenostoma appar- 

 ently can live indefinitely under favorable environmental con- 

 ditions without conjugation, autogamy, or endomixis. Indeed 

 its amicronucleate condition seems to preclude the possibility 

 of the occurrence of these phenomena. 



LITERATURE CITED 



Baitsell, G. A. 1912 Experiments on the reproduction of the hypotrichous 



Infusoria. I. Conjugation between closely related individuals of 



Stylonychia pustulata. Jour. Exp. Zool., vol. 13. 



1914 Experiments on the reproduction of the hypotrichous Infusoria. 



II. A study of the so-called life cycle in Oxytricha fallax and Pleuro- 



tricha lanceolata. Ibid., vol. 16. 

 BuscHKiEL, A. L. 1911 Beitrage zur Kenntnis des Ichthyophthirius multi- 



filiis Fouquet. Archiv f. Protistenk., Bd. 21. 

 Calkins, G. N. 1902 Studies on the life-history of Protozoa. I. The life-cycle 



of Paramecium caudatum. Arch. f. Entw. Mech., Bd. 15. 



1912 The paedogamous conjugation of Blepharisma undulans St. 



Jour. Morph., vol. 23. 

 Calkins, G. N., and Cull, S. W. 1907 The conjugation of Paramecium aurelia 



(caudatum). Archiv f. Protistenk., Bd. 10. 

 Enriques, p. 1903 Sulla cosi detta degenerazione senile dei Protozoi. Moni- 



tore Zool. ital., T. 14. 



1905 a Ancora della degenerazione senile negli Infusori. R. C. 



Accad. Lincei., T. 14. 



1909 a "Autorreferat" in Arch. f. Entw.-Mech., Bd. 27. 

 Feemor, X. 1913 Die Bedeutung der Encystierung bei Stylonychia pustulata 



Ehrbg. Zool. Anz., Bd. 42. 

 Haime, J. 1853 Observations sur les metamorphoses et I'organisation de la 



Trichoda lynceus. Annal. d. Sci. Nat., 3 S, T. 19. 



