OXYGEN AND MALE PRODUCTION 489 



support the contention that appreciable quantities of free oxygen 

 may be introduced into the new water with or within the cells of 

 Chlamy domonas . 



In the experiments in darkness of table 7 only 0.05 or 0.10 cc. 

 of Chlamydomonas was used which, of course, would have shown 

 lesser results in regard to oxygen if they had been tested than the 

 present experiments in which 0.5 cc. of Chlamydomonas was 

 used. 



DISCUSSION 



In the recent work by ShuU the summary of the results of the 

 experiments under normal air conditions and under the 40 per 

 cent and 60 per cent oxygen conditions show a higher per cent 

 of male-producing females produced under the 40 per cent and 

 60 per cent oxygen conditions than under air conditions. If, 

 however, one examines closely the individual experiments or lots 

 in the tables 1,2, and 5 of the results it is readily seen that the 

 higher per cent under the oxygen conditions is produced in 

 table 1 by the extraordinary results of two out of the six experi- 

 ments. In table 2 three experiments out of fourteen experiments 

 causes the higher per cent of male-producing females to be 

 obtained. In table 5 two experiments out of twenty experi- 

 ments of the oxygen-treated ones caused the total average per 

 cent of male-producing females to be twice as large as it would 

 have been without these two experiments. 



Some of the exceptionally favorable experiments under oxygen 

 conditions were paralleled with similar results under air con- 

 ditions in the controls. Thus indicating that the high per cent 

 of male-producing females produced in parallel lots in air and 

 in oxygen may have been due to other influences than an excess 

 of oxygen. In some of the experiments under oxygen conditions 

 no male-producing females at all were produced, while in many 

 others very few were produced. If the oxygen was a real in- 

 fluential factor in causing male-producing females to be pro- 

 duced, many ought to have been produced in every experiment. 



ShuU, however, does not claim that oxygen is the only factor 

 that causes an increase in male-producing females, but that, 



