226 GEORGE ALFRED BAITSELL 



tJoii occurred in this second beef culture. Inasmuch as the only 

 difference in the treatment of the two cultures lay in the media 

 used, there can be no doubt that the fundamental changes in 

 the life histories of the hay and beef cultures were induced 

 by the culture media. To quote from the former paper (p. 71): 



Inasmuch as conjugation never occurred at any time in the hay cul- 

 ture, even though in both the length of time it was kept and the number 

 of generations through which it passed it exceeded either of the cultures 

 kept on the beef medium, there is conclusive evidence that neither the 

 age of the organisms nor the number of generations through which 

 they passed were potent in inducing conjugation in these cultures. 

 The determining feature was the medium used and the results here re- 

 corded give definite evidence that the 'same protoplasm^ under the influence 

 of different culture media may show fundamental differences in its life 

 history. 



Calkins ('13), in some recent experiments on Paramaecium, 

 isolated the four cells resulting from the first two divisions of 

 an ex-conjugant and, later, when each of these four cells had 

 divided three times, forming eight cells, or 32 cells in all, he 

 again isolated them, forming four 'quadrants' of eight lines each 

 wfeich were continued as pure lines. During the time that the 

 animals have been under observation (about seven months) con- 

 jugation has been found to occur in only one of the 'quadrants.' 

 Calkins concludes from these results, but more particularly from 

 the fact that no conjugation has occurred in Woodruff's para- 

 maecium cultures during theu* long period under observation, ^ that 

 "some descendants of an ex-conjugant are potential germ cells, 

 others are not" or, in other words, that in paramaecia there are 

 conjugating and non-conjugating races, due to an inherent dif- 

 ference in the four cells derived from a single ex-conjugant. 

 However, Calkins in the preceding volume of this journal pre- 

 sents the results in a complete form. These show that conju- 

 gants have now been found in all the 'quadrants' of the original 

 J series. To quote from page 448: "The -\pril test brought a 

 surprise" in that animals from 'quadrants' B, C and D all gave 

 some conjugating pairs, as they also did in a second test later 



'For later results see article by Dr. Woodruff in this number. 



