THE EFFECT OF CONJUGATION IN PARAMECIUM^ 



H. S. JENNINGS 

 ' Zoological Laboratory of the Johns Hopkins University 



TWO FIGURES 



CONTENTS 



I. Introduction 280 



II. Methods: 'Split pairs'; 'pairs'; designation; culture; records; tabu- 

 lation and tables 282 



III. Effect of conjugation on multiplication, survival and variation 285 



Experiments with wild cultures: Paramecium caudatum 286 



Experiment 1: rate of fission; variation; mortality; abnormalities. . 286 

 Experiment 2: rate of fission; variation, mortality; abnormalities; 



summary of results 293 



Experiment 3 : effect of high temperatures 300 



Experiments with pure strains 302 



Race k 302 



Experiment 4 : Paramecium aurelia 304 



Experiments 5 to 14; comparative effects of repeated conjugation 



and of long abstention from conjugation 305 



Diagram of history of these experiments 307 



Experiment 5 308 



Experiment 6 309 



Experiment 7 314 



Experiment 8 314 



Experiment 9: fission rate; dimensions; determination of conjuga- 

 tion 315 



Experiment 10 317 



Experiment 11: 11 a; 11 6; 11 c; 11 d; 11 e; 11 /; 11 ? 318 



Experiment 12 : conjugation in a depressed stock 326 



Experiment 13: Production of inherited differentiation by conju- 

 gation 329 



Eight self-fertilizations 330 



Experiment 13 a: rate of fission; variation; mortality 332 



Experiment 13 b: inherited differentiations in the pure strain. . . . 333 



Experiment 13 c: conjugant lines; non-conjugant lines 340 



Summary of experiment 13 342 



' Fourth of a series of papers on Heredity, Variation and Evolution in Protozoa. 



279 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 14, NO. 3 

 APRIL. 1913 



