306 A. FRANKLIN SHULL 
line at the point where, in the corresponding family in table 8, 
the female was transferred to manure solution. 
The two tables (8 and 9) together show in an unmistakable 
manner that male-producers have been quickly excluded from the 
latter part of the families in table 8 by transferring the parents 
to manure solution. Only one of the young produced in the man- 
ure solution was a male-producer, and that one hatched from the 
very first egg laid after the transfer. This one case is important 
as indicating that the nature of a female is determined prior to 
the laying of the egg from which she hatches; or if that determina- 
tion is a gradual process, it has proceeded so far prior to the lay- 
ing of the egg that manure solution is unable to reverse it. 
Experiment 7. In this experiment a line was bred in manure 
solution. From each generation two sisters were reserved for 
breeding. One of these females was kept throughout life in 
manure solution, and all her offspring were reared to maturity 
in the same solution. The line thus reared consisted of 121 
individuals, all female-producers, showing that the manure solu- 
tion was strong enough to exclude male-producers from the fami- 
lies then being reared. 
The other female, of the two mederved for breeding, was kept 
in manure solution until she had laid from 1 to 16 eggs, and was 
then transferred to spring water, where she produced the rest of 
her family. The eggs laid in manure solution were hatched, and 
the young reared to maturity, in m&nure solution. The eggs 
laid in spring water were hatched, and the young reared to matur- 
ity, in spring water. The details of this experiment are given in 
table 10. The vertical line divides each family at the point where 
the parent was transferred to spring water. 
Many of the females hatched from eggs laid in spring water 
were male-producers, notwithstanding that their parents had 
previously been in manure solution strong enough to exclude male- 
producers. This indicates that the nature of a female is not 
determined in the very early (odgonial) stages of the egg from 
which she hatches. Of particular interest in this connection is 
the second family of table 10, from which it appears that the 
very first egg laid after the mother was transferred to spring water 
