ol6 
a. H. (iROSVENOR AND GEOFFREY SMITH. 
same limitafciou. The main i-esults of our experiments are 
given in tabular form on p. 621, 522. 
Table I gives the actual numbers of the males and females 
produced by parthenogenetic females when isolated in sepa- 
rate vessels and when crowded together in the incubator be- 
tween 25° and 30° C. (column H) ; at room temperature, about 
14° C, (R) ; and in an ice-chest between roughl}' 8° and 1° C. 
(C). In all, ten experiments are included. Nos. 2 to 12 in the 
first vertical column. These numbers refer to tlie particular 
females which were used as the original parents to start the 
lines of descent which were employed in the expei-iments. In 
the course of the experiments the actual pedigrees of every 
female used was known, but in Table I all the offspring of 
succeeding generations are summed and entered together 
according to whether they were produced from an isolated or 
crowded parent at room temperature, in the incubator or 
ice-chest. The offspring of the ten different lines are, how- 
ever, kept separate in the horizontal lines. The first total 
given in the first horizontal line below the table gives the 
grand total of males and females produced by all the diffe- 
rent lines. 
Thus the isolated females in the incubator gave rise to 1167 
individuals, all of which were females, no males being pro- 
duced. The isolated females at room temperature gave 323 
males to 1385 females, or 19’1 per cent, males, those in the 
cold chamber 10 males to 174 females, or 5’4 per cent, males. 
The crowded females in the incubator gave 286 males to 
657 fern lies, or 30’3 per cent, males ; those at room tem- 
perature gave 1631 males to 1487 females, or 52’3 per cent, 
males ; and those in the cold chamber gave 167 males to 226 
or 42'5 per cent, males. 
The most striking of these results is the entire absence of 
males in the broods of females kept isolated in the incubator. 
This occurred in six different lines of descent in which 
parallel cultures at other temperatures, or when the parents 
were crowded, gave a large proportion of males, so that it 
cannot be argued that special female-producing lines were by 
