N. CUNLIFFE 
21 
Duration and number of the nymphal stages at .>0 and 37 C. 
(a) Experimental Data. 
Some of the progeny of each female were reared in separate batches to the 
adult stage, to establish the duration and number of the nymphal stages. 
The records are summarised in Synopsis II, minimum, maximum and mean 
periods, together with the numbers of individuals observed, being given. As 
in 0. moubata, the larva 1 passes into the first nymphal stage without previous 
engorgement; from the first nymphal stage onwards, the periods required for 
ecdysis are reckoned from the date of the previous meal and not that of the 
previous moult. 
Synopsis II. Duration of stages in days. 
Stage 
Esg to larva 
Egg to 1st ® 
1st to 2nd ® 
2nd to 3rd ® 
3rd to 4th \ 
® or adult J 
4th to 5th \ 
® or adult f 
5th to 6th \ 
® or adult f 
6th to 7th \ 
® or adult J 
Ticks kept at 30° C. Ticks kept at 37° C. 
A _ _A- 
, „ 
No. of ' 
r 
No. of 
individuals 
individuals 
Min. 
Max. 
Mean 
observed 
Min. 
Max. 
Mean 
observed 
7 
28 
12 
709 
7 
11 
8 
231 
13 
32 
19 
630 
11 
20 
15 
198 
8 
30 
11 
348 
5 
11 
8 
121 
9 
18 
12 
184 
7 
11 
8 
8* 
® 7 
49 
14 
116 
3 21 
33 
29 
3t 
® 11 
25 
15 
63 
3 13 
22 
17 
29 
$ 16 
20 
17 
6 
® 15 
26 
17 
6 
3 14 
23 
18 
14 
$ 15 
19 
17 
12 
® 
No record 
$ 15 
— 
15 
2 
* These eight individuals were the only survivors out of 121 second stage nymphs and as third 
stage nymphs they refused to feed, 
t Probably abnormal. 
(6) Discussion of Data. 
As with 0. moubata , males appeared after four to six and females after 
five to seven ecdyses, 63 per cent, of the males appearing after the fifth ecdysis 
and 60 per cent, of the females after the sixth ecdysis. As, however, only 
66 individuals were reared to maturity, these percentages may require correc¬ 
tion. The mean minimum periods required for the metamorphosis of an 
individual from egg to adult, at 30 C., under laboratory conditions, are 
(1) for males, 60 ( corrected ), 73 or 89 days according to whether the indi¬ 
vidual undergoes four, five or six moults; 
(2) for females, 73, 88 or 103 days, the number of moults varying from 
five to seven. 
These periods are longer by an average of 27 days than in the case of 
1 The larva normally frees itself from the egg shell, but is otherwise inactive. In some cases, 
however, the species approaches O. moubata , inasmuch as the larva may undergo ecdysis without 
throwing off the shell. The feeble development of the hypostome, legs and claws and also the 
absence of eyes is doubtless correlated with the passiveness of this stage. 
