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THE AMERICAN NATURALIST [Vol. XLIX 



longitudinally in both the first and the second divisions 

 of the maturation process. The significance of the third 

 division is as obscure in Paramecium as maturation is in 

 some metazoan hermaphrodites. 



In parthenogenesis, finally, we are dealing with a bio- 

 logical phenomenon, not with an interpretation of par- 

 thenogenesis by Winkler or Strasburger or any other 

 individual, and to interpret this highly significant phe- 

 nomenon in Paramecium solely in the light of such defi- 

 nitions, as Woodruff and Erdmann do (p. 493), does not 

 carry conviction, nor does it conceal the real significance 

 of the phenomenon. Asexual endomixis in Paramecium 

 is parthenogenesis and nothing else, as Hertwig origi- 

 nally maintained in connection with these same phenom- 

 ena. Nor, except for the protozoa, is it a "new type of 

 parthenogenesis" for, if we accept conjugation as equiva- 

 lent to fertilization, its analogue is shown by the majority 

 of parthenogenetic eggs. 



In regard to conjugating and non-conjugating races of 

 Paramecium, Woodruff and Erdmann state : 



Thus it is proved that both the reorganization process and conjuga- 

 tion are potentialities of the same race — and therefore there is no evi- 

 dence for the view of Calkins ('13) that conjugating and non-conjugat- 

 ing races of Paramecium exist, or that " apparently some paramecia 

 are potential germ cells, others are not." 10 



This is rather a sweeping generalization to draw from one 

 pedigreed line in which conjugating animals appeared 

 only after six years in culture. If every Paramecium is 

 a potential germ cell, why was it that no pairs of conju- 

 gating aurelia were found during these six years? Or, 

 in Calkins and Gregory's observations on the first 32 

 cells and the pure lines arising from them, all from a 

 single ex-conjugant, why was it that all lines from one 

 quadrant gave epidemics of conjugation whenever the test 

 was made during a period of six months, while all other 

 lines from the remaining three quadrants failed to give 

 a single pair when tested under identical conditions? 



io Ibid., p. 490. Italics in the original. 



