22 
Ornithodorus savignyi 
0. moubata, reared under similar conditions. An increase in temperature of 
7° C. (from 30° C.) only reduced the period required for the production of 
third stage nymphs by 26 per cent. 
Duration and extent of engorgement . 
An experiment, similar to that carried out with 0. moubata, was conducted 
with this species, ten nymphs of different stages being kept under observation 
until they reached maturity. Their weights before and after engorgement and 
the times of attachment to the host were accurately recorded. Again there 
was no regularity in the time of attachment, observation on 29 individuals of 
all stages giving minimum, maximum and mean times of 10, 74 and 26 minutes 
respectively, at room temperature, about 16° C. The figures are in agreement 
with those of Drake-Brockman (1915). The mean time recorded for 0. moubata 
was 48 minutes, thus 0. savignyi is apparently a more rapid feeder. Of the 
ten nymphs under observation, only four reached maturity, one being male 
and three female. In the female series, the mean increase in weight in grams 
was (a) before the final moult, 0-0647, and (b) after the moult 0-2202; the 
corresponding figures for the solitary male were (a) 0-0528, and (b) 0-0246. 
None of these figures were reached by 0. moubata. 
The influence of moisture on vitality and ecdysis. 
A similar experiment to that carried out with 0. moubata proved that, 
for this species also, excess of moisture is injurious to the individual. A batch 
of 33 first stage nymphs from the same female was divided into three lots, 
which between meals were maintained at 30° C. in saturated, moist and dry 
atmospheres respectively. A summary of the experimental records 1 is given 
in the following table, in which are shown the minimum and maximum 
number of days required for ecdysis, with the mean in brackets and the 
number of individuals observed in square brackets: 
% of ticks 
which 
Atmosphere 
2nd ® 
3rd ® 
4th ® 
5th ® 
6th ® 
matured 
Saturated 
9—13 (11) 
11—14(13) 
23—48 (40) 
21 
— 
9% 
[11] 
[11] 
[7]1<J 
[1] 
Moist 
7—8 (8) 
9—32 (12) 
10—18 (12) 
11—17(14) 
— 
27% 
[11] 
[11] 
[11] 2 ^ 
[4] 1 3 
Dry 
7—9 (7) 
9—13 (10) 
11—16(12) 
10—14(12) 
13—17 (15) 
45% 
[11] 
[8] 
[8] 1 c? 
Of 
r-H 
*6 
<N 
O 
[2] 19 
Excess of moisture was therefore a decidedly unfavourable factor, as under 
this condition only 9 per cent, of the ticks matured, whereas in the dry 
atmosphere 45 per cent, matured. The ecdysis period was not markedly 
affected by the presence of moisture ( vide Synopsis II), until after the third 
nymphal stage was attained, when the lack of vitality was indicated by a 
lengthening of this period. 
1 The 1st nymphs were fed on 17. i. 13 and the 5th nymphs were fed or offered a meal on 
13. vi. 13. 
