I96 W. V. LAMBERT, W. S. RICE, AND H. C. A. WALKER. 



Table I. 



females were isolated every other day for making the counts on 

 the two races. The average number of young daughter-females 

 produced in each forty-eight hour period at this time was ex- 

 tremely variable. The mothers of the A race during this period 

 produced an average of 6.84 daughter-females while those of the 

 B race produced an average of only 5.81. 



The two parthenogenetic races were then carried on parallel 

 with each other until the beginning of the forty-third generation 

 at which time another series of observations was started on the 

 number of young daughter-females each mother would produce 

 in a given length of time, approximately 48 hours. As new 

 generations were isolated great care was taken to pick uniform- 

 sized daughters. One investigator did all of the isolating during 

 this series of counts in order to insure the greatest uniformity. 

 Considerable difficulty was experienced during this series of obser- 

 vations because of the large per cent, of male-producing females. 

 These had to be discarded for only the mothers producing 

 daughter-females were considered in calculating the averages. 



The A race during this second series of observations produced 

 an average of 7.58 daughter-females while the B race produced 

 8.88. Considerable variation occurred throughout the different 

 generations, but the variations were less in this instance than 

 they were in the preceding series of observations. A complete 

 record of the results of this observation can be seen in Table II. 



The two races were then carried on for fourteen generations 

 before another series of observations was begun. At the begin- 



