CONJUGATION AND ENCYSTMENT 359 



remained fairly constant throughout the remainder of the ex- 

 periment, 315 days. During this time one set produced an 

 average of 838 generations per Hne, 2f per day, the other an 

 average of 634 generations per line, 2 per day. 



LITERATURE CITED. 



BttxscHLi, O. 1876 Studien liber die ersten Entwicklungsvorgange der Eizelle, 

 die Zellteilung und die Konjugation der Infusorien. Abhdlg. Senken- 

 berg. Naturf. Ges., 10. 



Calkins, G. N. 1909 Protozoology. 349 pp. New York. 



1915 Didinium nasutum. I. The Life History. Jour. Exp. Zool., 

 voL 19, pp. 225-239. 



1916 General biology of the protozoan life cycle. Am. Nat., vol. 50, 

 pp. 257-270. 



Calkins, G. N. and Gregory, Louise H. 1913 Variation in the progeny of a 



single exconjugant of Paramecium caudatum. Jour. Exp. Zool., vol. 



15, pp. 467-525. 

 Engelmann, T. W. 1876 Ueber die Entwicklung und Fortpflanzung von Infu- 

 sorien. Morph. Jahrb., Bd. 1, S. 573-634. 

 Erdmann, Rhoda and Woodruff, L. L. 1916 The periodic reorganization 



process in Paramecium caudatum. Jour. Exp. Zool., vol. 20, pp. 59-83. 

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



Zool. Anz., Bd. 42, S. 380-383. 

 Hertwig, R. 1889 Ueber die Konjugation der Infusorien. Abhdlg. d. II. 



CI. d. konigl. bayr. Akad. d. Wiss., Bd. 17, (Abth. 1), s. 151-233. 

 Jennings, H. S. 1910 What conditions induce conjugation in Paramecium? 



Jour. Exp. Zool., vol. 9, pp. 279-300. 



1913 The effect of conjugation in Paramecium. Jour. Exp. Zool., 



vol. 14, pp. 279-391. 

 Maupas, E. 1888 Recherches experimentales sur la multiplication des infu- 



soires cilies. Arch. d. Zool. Exp. et G^n. (2), T. 6, pp. 165-277. 



1889 Le rajeunissement karyogamique chez les cilies. Arch. d. Zool. 

 Exp. et Gen. (2), T. 7, pp. 14^-517. 

 Pra.vdtl, H. 1906 Die Konjugation von Didinium nasutum. Arch. f. Pro- 



tistenkunde, Bd. 7, S. 229-258. 

 Woodruff, L. L. 1911 Two thousand generations of Paramecium. Arch. f. 



Protistenkunde, Bd. 21, S. 263-266. 



1912 A five-year pedigreed race of Paramecium without conjugation, 

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1913 Dreitausend und dreihundert Generationen von Paramecium 

 ohne Konjugation oder kiinstliche Reizung. Biol. Centb..Bd. 33, 

 s. 34-36. 



1914 So-called conjugating and non-conjugating races of Paramecium. 

 Jour. Exp. Zool., vol. 16, pp. 237-240. 



Woodruff, L. L. and Erdmann, Rhoda 1914 A normal periodic reorganiza- 

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 vol. 17, pp. 425-518. 



