148 THE AMEBIC AN NATURALIST [Vol. XLIV 



Table II 



Parth. 9- Percent. Sex 



From the third generation of the series in spring water 

 in Table II, a female was returned to the concentrated 

 filtrate, and her progeny reared for three generations. 

 A control was continued in spring water. The results 

 arc those in Table III. 



Table III 



Sex. 9. Parth. 9. Per cent. Sex. 9 . Sex. 9. Parth. 9- Percent. Sex. 9. 



' 7 I 110 I 5.9 107 | 0.0 



The experiment was repeated four times, with sisters 

 in each case, derived from lines more or less distantly 

 related to those in the preceding experiments. These 

 are recorded in Table IV. 



Table IV 



In every case, the evidence points to the same con- 

 clusion, namely, that the filtrate from the old cultures 

 reduces the number of sexual females. The losses by 

 deatli are too few to account for the results obtained, 

 and there is evidence to show that what deaths there are 

 are not selective. 



It is interesting to note the bearing of the above evi- 



