240 LORANDE LOSS WOODRUFF 



The race that I worked with in 1901 was a conjugating race which died 

 out in the 742d generation. Woodruff's long hne of over 3500 genera- 

 tions is a non-conjugating race and the two races cannot be compared 

 in regard to vitahty, since normal conjugation was prevented in the 

 conjugating race, whereas in the non-conjugating race there has been 

 no artificial prevention of a normal process.^ 



In an extensive paper on physiological variations in Paramae- 

 eium, Calkins and Gregory reiterate the same point of view : 



To return to Woodruff's race of Paramaecium aurelia, we find this 

 important difference between his material and that which Calkins worked 

 with. The Paramaecium caudatum which formed the material for the 

 earlier observations was a conjugating line as shown by conjugation 

 tests made from time to time. In this line, therefore, a normal func- 

 tion — conjugation — was inhibited; metabolism weakened steadily until 

 physiological death carried off all of the race not artificially stimulated. 

 Finally, "germinal death" preceded by the degeneration of the micro- 

 nucleus and the cortical plasm, carried off the last individual 



In Woodruff's material on the other hand, the race is non-conjugating, 

 hence no normal function has been suppressed by keeping the individual 

 apart. So far as known the life history of such non-conjugating forms 

 has never before been undertaken and Woodruff has shown that they 

 will live for at least five and one-half years. ^ 



The fact that conjugation has now occurred in mass cultures 

 from my pedigreed race demonstrates that the race is a conju- 

 gating 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 existence must plan to carry a race for far more 

 than 4102 generations without a tendency to conjugation being 

 manifested. 



« G. N. Calkins, Proc. Soc. for Exper. Biol, and Med., vol. W, 1913, p. 67. 

 ' Calkins and Gregory, loc. cit. 



