\\VMAX REED GREEX. 



to the basis of the individual, the data on the first, second, and 

 third groups being given in the first, second, and third columns 

 respectively, of the table. 



Comparing these three groups we find that the differences when 

 averaged are not great enough to be significant. The members 

 of the third group lived roughly two and one half times as long 

 as the others, and should we reduce the data to a common unit 

 of time the correspondence would be very close. For instance, 

 the number of broods produced by the 1 first group per unit of 

 time, say 27 days, would be 10 (2.25 X 3.6 = 10.00), while the 

 third group produces just 10.6. The number of female broods 

 produced by the first group would be 4.72 (2.25 X 2.1 - 4.72), 

 as against 5.2 broods produced by the third group, etc. As to 

 all of the main points under consideration the figures agree so 

 closely that we must conclude that the kind of water in which 

 the three groups were reared and the relative food supply had 

 little or nothing to do with the ratio of sexes. In the general 

 discussion of this experiment further data are given based on the 

 observation of isolated females whose ancestry is now known for 

 one or two generations, with conclusions regarding. the relation 

 of sexual to asexual females, males to ephippial egg production, 

 etc. It is deemed better however, to defer this until after the 

 presentation of another general isolation experiment in which 

 stem mothers were used instead of females selected from the 

 general cultures. 



Experiment j. Although most of my experiments to induce 

 ephippial eggs to hatch have been failures I have given them in 

 detail further on in this paper because of the fact that so little 

 has been accomplished along this line. I have succeeded in 

 securing about 70 stem mothers and have had a lair degree ot 

 success in rearing them. All of these were isolated at once and 

 a complete record was kept of the number oi broods, the kinds of 

 individuals in each brood, length of life, etc., as shown in the 

 table below. It was found that a large number died early, pro- 

 ducing few or no offspring. A few however produced as many as 

 9 broods. The average number of broods produced per stem 

 mother was slightly over 6. Hence in the tabulation oi results no 

 account was taken of stem mothers \\hose broods were loo lew, 



