MALE-PRODUCTION IN HYDATINA 



533 



much water (without Euglena) from the Euglena stock as was 

 introduced into the first dish with Euglena. It was easy to 

 obtain this water practically free of Euglena, since the Euglena 

 was a quiescent form that produced an incrustation along the 

 sides of the jar, while very few individuals were actively swimming. 

 The parent rotifers were removed from their dishes from 

 twenty-four to forty hours later. All young rotifers hatching 

 from eggs laid in that time were reared to maturity, in all three 

 lots alike, in spring water with manure scum as food. The male- 

 producers and female-producers are recorded in table 5. 



TABLE 5 



Comparison of the effects of Euglena and manure scum as food, and of oxygenated 

 and untreated loater, upon the proportion of male-producers in the rotifer 



Hydatina senta 



March 20 



March 22 



March 23 



March 26 



March 28 



March 29 



April 2 



April 4 



April 16 



April 18 



April 19 



April 23 



April 25 



April 26 



April 30 



May 2 



May 3 



May 7 



May 9 



May 14 



Totals 



Percentage of c?' 9 



EUGLENA AS FOOD IN 

 UNTREATED WATER 



Number of Number of 



d"^ 9 9 



13 



21 



14 



29 



3 



25 



4 



14 



1 



1 



3 



6 



















1 



2 



4 







141 



43 

 33 

 18 

 28 

 27 

 55 

 62 

 61 

 46 

 16 

 68 

 27 

 47 

 34 

 57 

 32 

 25 

 43 

 67 

 29 



818 



14,7 



MANURE SCUM IN OXY- 

 GENATED WATER 



Number of 



0^9 



1 

 15 

 

 1 

 5 

 2 

 4 

 4 

 

 23 

 

 

 5 

 3 

 

 1 

 9 

 

 

 1 



74 



Number of 



9 9 



22 

 33 

 22 

 29 

 9 

 77 

 41 

 64 

 28 

 45 

 53 

 20 

 51 

 47 

 31 

 86 

 26 

 47 

 41 

 21 



793 



8,5 



MANURE SCUM IN UN- 

 TREATED WATER 



Number of Number of 



0^9 9 9 



2 

 1 

 

 

 

 3 



10 

 

 



13 

 3 

 

 4 

 

 

 

 3 

 1 

 

 



40 



37 

 21 

 21 

 18 



1 

 74 

 44 

 59 

 35 

 58 

 57 



5 

 30 

 54 

 40 

 69 

 46 

 18 

 50 

 20 



757 



5.0 



