82 RHODA ERDMANN AND LORANDE L. WOODRUFF 



and Hertwig, that conjugation is unnecessary for the indefi- 

 nite life of Paramaecium under favorable environmental con- 

 ditions. 



To Hertwig's and Calkins' recent contentions that their con- 

 clusion was correct and Woodruff's was wrong, we would reply, 

 that the reorganization process (endomixis) is not conjugation 

 and no one had any other phenomenon than conjugation — in- 

 volving syncaryon formation — in mind until Woodruff and Erd- 

 mann discovered endomixis — in which a syncaryon is not formed. 

 To say that endomixis fills essentially the same role in the life 

 history of the infusorian as conjugation is to beg the entire 

 question. Had Hertwig worked out the stages which he found 

 over twenty-five years ago, or realized their general significance, 

 and had he related these with rhythms ten years ago when they 

 were discovered, the problem would have been cleared up then. 

 The aspect of the problem has changed with the discovery of 

 endomixis. The question is now not whether conjugation is 

 necessary — for Woodruff has shown that it is not — but whether 

 endomixis, a new phenomenon which Woodruff and Erdmann 

 have shown to exist, is necessary. 



Whatever the answer afforded by future work to this new 

 question may be, it is clear that conjugation — and by this always 

 was meant, and always is meant, the formation of a syncaryon — 

 is not necessary, since an individual Paramaecium is self-suffi- 

 cient to reproduce indefinitely without recourse to conjugation, 



VI. LITERATURE CITED 



(For a more extensive bibliography, cf. Woodruff and Erdmann, 1914 (III), 

 pp. 498-502.) 

 Calkins, G. N. 1904 Death of the A-Series of Paramaecium caudatum. 



Conclusions. Jour. Exp. Zool., vol. 1. 



1915 Cycles and rhythms and the problem of 'immortality' in 



Paramaecium. Amer. Naturalist, vol. 49. 

 Calkins, G. N. and Cull, S. W. 1907 The conjugation of Paramaecium cau- 

 datum. Arch. f. Protistenk., Bd. 10. 

 Erdmann, Rh. 1908 Kern- und Plasmawachstum in ihren Beziehungen zu 



einander, Ergeb. d. Anat. u. Ent., Bd. IS. 

 Erdmann, Rh. and Woodruff, L. L. 1914 Vollstiindige periodische Erneuerung 



des Kernapparates ohne Zellverschmelzung bei reinlinigen Paramae- 



cien. Biol. Cent., Bd. 34, 8. 



