N. ClJNLIFFE AND Gr. H. F. NUTTALL 
337 
tion of the host’s skin. During these experiments, taking the nymphal stages 
1 to 6 in order, the minimum number of days elapsing between emergence 
and feeding were 5, 2, 2, 1, 3 and 7 respectively, but no special attempt was 
made to induce early feeding in any case. 
Successful ecdysis seems to be dependent on the extent of the previous 
meal and in the case of 0. moubata never occurs prior to engorgement, at any 
stage of the life-history (excepting larva to first nymph). Iierms’ (1916) 
statement therefore, that the first stage nymph of 0. coriaceus Koch moulted 
to the second stage nymph, without previously feeding, if confirmed, would 
be of interest. 
The two points for consideration in the gorging of ticks are (1) the time 
of attachment to the host and (2) the quantity of blood they are capable of 
absorbing/ Merriman kept four ticks under observation from the first nymphal 
stage until they reached maturity and recorded their weights before and after 
engorgement and the times of attachment to the host. His records showed 
that the time of attachment was approximately the same with all stages; 
taken collectively, the minimum, maximum and mean times were 25, 74 
and 48 minutes respectively, at room temperature, about 16° C. The period 
of starvation had no influence on the time required for engorgement nor was 
the feeding period correlated with the amount of blood absorbed. 
The mean increases in weight in grams were 0-0011, 0-0040, 0-0084 and 
0-0361 for the first four nymphal stages. The two fifth stage nymphs, which 
gave rise to females, showed a mean increase in weight of 0-0528 gram and 
after reaching the adult state of 0-1349 gram. The two males which emerged 
from the fourth nymphal stage showed a mean increase of 0-0076 gram 
only. 
Merriman therefore concluded that the female fed chiefly after reaching 
maturity, for the purpose of egg maturation and that the male required 
most food in the last nymphal stage for the production of spermatozoa. To 
test this conclusion, ten nymphs were reared separately from June 1913 
onwards, Merriman’s observations being repeated, but in this case the ticks 
were maintained at 30° C. between meals. Six individuals were female and 
four male. In the female series, the minimum, maximum and mean increases 
in weight in grams were (a) before the final moult, 0-0158, 0-0432 and 0-0272 
and (b) after the moult 0*0062, 0-1310 and 0-0492; the corresponding figures 
for the male series were (a) 0-0158, 0-0164, 0-0122 and (b) 0-0066, 0-0296, 
0-0166 grams respectively. For the ten ticks, the period required for moulting 
varied between eight to ten days only, although the quantities of blood 
absorbed varied very considerably. 
It would appear therefore that the adult of either sex may take its largest 
meal either before or after reaching maturity, the extent of the meal probably 
depending on the vitality of the individual. This view is supported by the 
time records. These show that the ticks which fed heavily secured a suffi¬ 
ciency in short periods of time, e.g. one female gained 0-1012 gram in 23 
