46 R. T. YOUNG 



Experiment 14 (fig- XIV) 



On 5/25 line XIV was branched off from line IV and carried with 

 daily slide changes through thirty-two generations until 6/5. Endo- 

 mixis occurred on 5/26 and 6/3 with an intervening period of twenty- 

 one generations as compared with one of seventy-six in the parent 

 line. 



Experiment 15 (fig. XV) 



On 6/6 fine XV was branched off from line XIII and carried through 

 thirty-six generations with daily slide changes until its death on 6/18. 

 Endomixis occurred on 6/7 and 15 with an interval of twenty-six 

 generations, as compared with a period of seventy-nine (eighty) gen- 

 erations 13 ' 14 without endomixis in the parent line. 



Experiment 16 (fig. XVI) 



In this experiment line XVI was branched off from line Ha on 5/29 

 and carried through sixty-one generations with daily slide changes 

 until its death on 6/18. Endomixes occurred on 5/30, 6/8 and 6/17 

 with intervening periods of thirty-three and twenty-five generations 

 respectively, while in the parent line, Ha, seventy-eight generations 

 intervened between two successive endomixes. 



Experiment 17 (fig. XVII) 



Line XVII was started from line VI on 5/29 and carried through 

 three generations only with daily alide changes until its death on 6/1. 

 Endomixis ensued on 5/30 with no generations before its occurrence, 

 while in the parent line there were thirty-seven generations before its 

 next occurrence. 



Conversely I have tried the effect of lowering the temperature 

 from room temperature (approximately 20°), and from 30° to 14°. 

 In none of the few experiments of this character which I have 

 performed have I succeeded in inducing endomixis. I have not 

 however carried the experimental lines through a sufficient num- 

 ber of generations to ascertain whether or not lowering the 

 temperature would influence the frequency of its occurrence. 



I have also performed a number of experiments with various 

 chemicals (ammonia, alcohol, urea; strychnine and nicotine), 

 but in no case have I succeeded in definitely inducing endomixis 

 or increasing its frequency. In most of these experiments, 

 however, the race has not lived long enough to enable me to 

 make any final statements regarding the influence of such 

 experiments on endomixis. 



