280 DAVID DAY WHITNEY 



cc. bouillon, 2 cc. stable tea, and 138 cc. tap water) in which there 

 were growing a mixed culture of various green flagellates many 

 male individuals appeared within a few days. 



The average percentage of males produced in this species is 

 lower than it is in the preceding species. This may have been 

 due to the inferior quality of these flagellates as a food for this 

 particular species of rotifer, or as these rotifers are also bottom 

 feeders perhaps they could not obtain a superabundance of food 

 as many of the flagellates were more or less free-swimming. 



These experiments were all done at room temperature on a 

 table in subdued light. Diagrams of a female and a male rotifer 

 and the different eggs are in figure 4, a plotting of experiment 

 20 is in diagram 5, and the details and the results of the experi- 

 ments are in table 4. 



Pedalion mirum 



In February of 1915 some of the same dried mud that was 

 collected at Cold Spring Harbor in 1908 and produced Brachionus 

 pala in February of 1915 was put into weak stable tea water 

 (3 cc. stable tea added to 147 cc. water) and after a few days 

 several females of the jumping rotifer, Pedallion mirum were 

 found. After considerable experimenting a suitable method 

 was found by which large numbers of these rotifers could be 

 readily reared. 



In some experunents weak solutions of stable tea alone were 

 used and in others bouillon was added to the stable tea solu- 

 tion. All the cultures were inoculated with a miscellaneous 

 collection of green flagellates and then kept in direct sunlight 

 as much as possible. The temperature was not allowed to rise 

 above 37°C. This was rendered possible by placing the cul- 

 ture jars in a large pan through which water flowed from the tap. 

 At night, however, the temperature was that of the room, 20°C. 



After the cultures had been progressing for a few days the 

 flagollates, mostly Chlamydomonas, and the rotifers became 

 more or less balanced and only female rotifers occurred. How- 



