MALE-PRODUCTION IN H^TDATINA 541 



in the darkness were aerated, others not, and he appears to have 

 suspected that if oxygen were a male-producing agent, the more 

 oxj^gen there was present the more males there should be. In 

 the experiments described in this paper there is little difference, 

 in its effect on male-production, between water saturated with a 

 40 per cent oxygen atmosphere and water saturated with a 60 per 

 cent oxygen atmosphere, although it was shown that 60 per cent 

 oxygen atmosphere left the oxygen content of the water very 

 plainly greater. '\^Tiat difference 'there was indicated that the 

 lower concentration of oxygen was the more effective. It can- 

 not be accepted without question, therefore, that aeration of the 

 water, in addition to the use of green food with its incidental 

 oxygen, sh(mld further increase the male-production. 



Disregarding the above objections to the experiments on which 

 table 5 of Whitney's paper is based, we may examine the results 

 of those experiments. Instead of comparing only selected parts 

 of his table 5, the whole table may be included. Since in some 

 of the cultures more mothers were used than in others, merely 

 adding together the offspring of parents that were treated in the 

 same manner would give to those cultures having many mothers 

 undue weight. A more just method of combining like cultures is 

 to average the percentage of male-producers in all cultures; each 

 culture is then as weighty as the others, regardless of the number 

 of parents used. By this method of combination, Whitney's 

 table 5 is converted into the following: 



Per cent 

 male-producets 



Sunlight, with aeration .54 . 5 



Darkness, with aeration 19.0 



Darkness, without aeration 40 . 6 



It is difficult to see what these results mean, though Whitney 

 concludes from them that oxygen is not a male-producing agent. 

 Just whj^ one is to infer that the quantity of food is the cause of 

 the differences shoM'n, is equally obscure. The argument for 

 oxygen is at least as good as the argument for food. 



The remainder of WTiitney's paper is devoted mainly to the 

 effect of oxygen upon the protozoan and bacterial food supply 

 of the rotifers in experiments like those of Shull and LadofT. He 



