264 JVotes on the Biology of Pediciilus humaiius 
Fourth Generation. Broods from lice taken from the third genera¬ 
tion. The numbers refer to the number of the experiment in that 
generation. 
( 2 ) 2 (cJcJ) X 8 $ (d?); 5 nymphs hatched, of which only 1 became 
adult. Male brood (?). Id 
(4) 2 d (dd) X 5 ? (?$); 37 nymphs hatched, of which 13 became j 10$$ 
adult. Mixed brood. ( 3dd 
( 6 ) 3 d (dd) X 13 $ ($$); 30 nymphs hatched, of which 14 became 
adult. Male brood. 14 dd 
H) 2 d (dd) X 5 $ ($$); 16 nymphs hatched, of which 3 became 
adult. Female brood. 3 $$ 
( 8 ) 2 d (dd) X 5 $ ($$); 36 nymphs hatched, of which 11 became 
adult. Male brood. 11 dd 
(14) 2d(dd) X 7$(d$); 29 nymphs hatched, of which 10 became (9dd 
adult. Male brood (? mixed). (1 $ 
(16) 2d(dd) ^ 1$(d$); 18 nymphs hatched, of which 3 became 
adult. Female brood. 3 $$ 
(17) 2d(dd) X 5 $($$); 24 nymphs hatched, of which 2 became 
adult. Male brood. 2dd 
Some of the individuals from these experiments were used again 
for the two following: 
(2/6) 2d(dd)(hoDi Exp. 2 of this generation) x 13 $ ($$) (from 
Exp. 6 of this generation); 10 nymphs emerged, of which 4 became j 3 $$ 
adult. Mixed brood. (1 d 
(7/14) 2 d (dd) (from Exp. 7 of this generation) x 7 $ (d$) (from 
Exp. 14 of this generation); 11 nymphs emerged, of which 5 became (4 dd 
adult. Mixed brood. (1 $ 
Fifth Generation. Broods from lice taken from the fourth genera¬ 
tion. The numbers refer to the number of the experiment in that 
generation. 
(2) 7/14 d (d?) X 7 $ ($$); 4 nymphs hatched and only one $ 
became adult. 1 $ 
(3) 7/14 d (d$) X 7 $ ($$); 16 nymphs hatched and 4 became adult. ‘ *$ 
Mixed brood. 
(13) 6d (dd) X 2/6$(d$); 8 nymphs hatched, and 4 became adult. 
Female brood. 
4$$ 
During the last two generations the lice gradually became weaker 
and only a few eggs were laid, most of which were sterile. 
The experiment was discontinued at this stage as the few adults 
that were left alive were so feeble that they would not have been capable 
of reproduction. 
