author's abstract of this papeu Issued 

 by the bibliographic service, june 2 



THE INEFFECTIVENESS OF OXYGEN AS A FACTOR 



IN CAUSING MALE PRODUCTION IN 



HYDATINA SENTA^ 



DAVID D. WHITNEY 



Department of Zoology, University of Nebraska, Lincoln, Nebraska 



Recent papers by Shull and Ladoff ('16) and Shull ('18) main- 

 tain that a sufficient amount of dissolved oxygen in the culture 

 water will cause an increase in the production of males in the 

 rotifer Hydatina senta. Whitney ('17) explained these results 

 obtained by Shull and Ladoff as being due to the effect of oxygen 

 upon the food supply which in turn effected the production of 

 males. Later, Shull made further experiments which seem to 

 demonstrate that oxygen is really a potent influence in causing 

 males to be produced. Not being convinced, however, that the 

 problem was finally settled, new experiments were undertaken 

 by the author, which in their turn seem to show that oxygen in 

 itself is not efTective in causing males to be produced. 



METHOD 



In all of the experiments old culture water was used which 

 had been made out of rain water and horse manure several weeks 

 or months previous to the beginning of the present experiments. 

 This culture water was such th^t when it was a few weeks old 

 rotifers readily lived in it, and they also lived in it just as readily 

 when it was several months old provided food was put into it. 



The best food supply in these experiments seemed to be a 

 mixture of green flagellates, Chlamydomonas, and colorless flag- 

 ellates, Polytoma. A pure diet of Chlamydomonas used for 

 several successive days was detrimental to the rotifers. Many 

 of them would gorge themselves on this food so that their stom- 

 achs would burst and allow the contents to fill the whole body 



1 Studies from the Zoological Laboratory, Tiie University of Nebraska, no. 121 . 



469 



