536 



A. FRANKLIN SHULL 



TABLE 7 



SJiowing the effects of oxygen, Euglena, and creatin upon the proportion, of male- 

 producers in a Nebraska line of the rotifer Hydatina senta 



May 16. 

 May 17. 

 May 21. 

 May 23. 

 May 24. 

 May 28. 

 May 30. 

 May 31. 

 June 4. 



Totals 



STRENGTH 



OF 



CREATIN 



SOLUTION 



IN PER 



CENT 



0.01 



0.02 



0.01 



0.01 



0.02 



0.02 



0.03 



0.025 



0.02 



Percentage of cf 9 



EUGLEN.^ AND 

 CREATIN 

 SOLUTION 



Num- 

 ber of 



cf 9 





 

 4 

 

 18 

 17 

 

 9 

 4 



52 



Num- 

 ber of 



99 



18 

 21 

 14 

 19 

 14 

 24 

 10 

 30 

 17 



167 



23.7 



MANURE SCUM 



AND OXYGEN- 



.\TED CREATIN 



SOLUTION 



Num- 

 ber of 

 6^9 



12 



Num- 

 ber of 



99 



23 

 2 

 29 

 24 

 13 

 19 

 43 

 40 

 21 



214 



5.3 



MANURE SCUM 



.^ND UNTREATED 



CRE.^TIN 



SOLUTION 



Num- 

 ber of 



^■9 



13 



Num- 

 ber of 



9 9 



26 

 17 

 25 

 32 

 21 

 41 

 27 

 55 

 47 



291 



4.2 



M.YNURE SCUM 

 AND UNTRE.\TED 

 SPRING WATER 



Num- 

 ber of 



cf 9 





 

 

 

 

 2 

 9 

 3 

 10 



24 



Num- 

 ber of 



99 



26 

 9 

 21 

 35 

 19 

 42 

 43 

 63 

 61 



319 



6.9 



Manure scum was added as food, and the dish was set under a 

 bell jar in an atmosphere of which 40 per cent was oxygen. 

 3) A third dish was filled with the dilute creatin solution, manure 

 scum was added as food, and the dish set in air. 4) The fourth 

 dish, as general control, was filled with untreated spring water, 

 manure scum was added as food, and the dish was set in air. 



After from twenty-four to forty hours the rotifers were re- 

 moved from the dishes. The offspring hatching from eggs laid 

 in that period were reared to maturity in spring water, being fed 

 with manure scum. 



The rotifers used in this experiment were received from Prof. 

 D. D. Whitney, who collected them at Lincoln, Nebraska. 



Experiment 6. This is a duplication of experiment 5 in every 

 respect, except that the rotifers used were part of a line received 

 from Prof. A. L. Treadwell, who in turn obtained them from 

 Prof. D. D. Whitney, then at Wesleyan University. They are 

 presumably from the same New Jersey stock as was used in Dr. 

 Whitney's former work. All the preceding experiments in this 



