PROCEEDINGS OF THE OHIO ACADEMY OF SCIENCE. 351 



cultures ; and Calkins could hold that "Woodruff's Paramaecium 

 aurelia is evidently a Paramaecium Methuselah belonging to a 

 non-conjugating line the life history of which is not known in 

 any case". But two years ago conjugation set in vigorously in 

 the control cultures ; and Woodruff replies : "The fact that con- 

 jugation has now occurred in mass cultures from my pedigreed 

 race demonstrates that the race is a conjugating race when the 

 proper conditions for its consummation are realized. Therefore 

 there is no evidence extant that a non-conjugating race of 

 Paramaecium exists. One who now would demonstrate its exist- 

 ence must plan to carry a race for far more than 4102 generations 

 without a tendency to conjugation being manifested". 



A consecutive cytological study of this strain of para- 

 moecium has shown a remarkable type of nuclear reorganization 

 to which Woodruff gives the name of "endomixis" and to which 

 he attributes the undying character of the protozoa. From these 

 results he concludes : "Paramaecium aurelia can reproduce in- 

 definitely without conjugation under favorable environmental 

 conditions. The so-called life cycle is non-existent * * * 

 From the life history of this race of Paramaecium aurelia we 

 lean toward the view that both endomixis and conjugation in 

 the infusoria, as fertilization in the higher forms, have a double 

 significance — both afford the opportunity for molecular rear- 

 rangement which leads to increased physiological activity, and 

 the opportunity for variation. The life of the paramaecium race 

 can proceed indefinitely with endomixis under favorable environ- 

 mental conditions — conjugation being unnecessary. 'Senile 

 degeneration' and 'physiological death' are not the inevitable 

 result of continued reproduction without conjugation, — the cell 

 has an internal regulatory phenomenon, endomixis, which is self- 

 sufficient for the life of the race". 



The last word has, perhaps, not been spoken ; but the present 

 evidence seems to point toward the old Weismannian view of 

 protozoan undyingness. 



But fascinating as are such theoretical studies, no less fasci- 

 nating and, perhaps, no less important in establishing the new 



