Gr. H. F. Nutt ALL 
419 
some days that are attractive to $s. A certain amount of atmospheric 
humidity is required during metamorphosis-, the time required for 
development from egg to larva is 47-63 days at 30° C. [Lounsbury 
gives 77-81 days in summer, 185 days in winter]; metamorphosis from 
larva to nymph takes place in 12-13 days at 30° C., in 16 days at 37° C. 
[Lounsbury states that 23-84 days are required if the ticks are kept 
cool]; metamorphosis from nymph to adult takes place on 18-21 days 
at 30° C., in 44 days at 37° C. [Lounsbury gives 28-98 clays at low 
temperatures; development is retarded at 35-41° C.]. There was not 
much loss of life during this stage, thus 102 adults emerged from 106 
nymphs in one case and 825 issued from 1145 nymphs in another. 
My figures seem to show a distinct preponderance of $s-, thus among 
1242 adults, descended from a single ?, there were 747 d and 495 $. 
The gorged and fecundated $s begin ovipositing 8-11 days after abandon¬ 
ing the host if they are maintained at 30° C. [Lounsbury found that 
oviposition commenced in winter after 70-74 days]; the ?s may survive 
for 1-15 days after the process is completed, oviposition having lasted 
24-35 days [51-55 days in winter according to Lounsbury]. The 
? lays 12,300-18,500 eggs. The longevity of the unfed tick is marked, 
in onr experiments several lots of larvae lived for upwards of 346 days, 
nymphs lived for 250 days and some adults (d) survived for upwards of 
660 days at room-temperature. Adults after fasting 412 days and 
upwards have fed normally upon a ram, the sexes have paired as usual 
and the $s have oviposited. Our strain of A. hebraeum (N. 1732) was 
raised in the laboratory through two generations; the life-cycle of the first 
generation was completed in 240 days, that of the second generation 
in 171 days. [Lounsbury (1, 4) states that at least 9 months (ca. 270 
days) are required to complete the life-cycle; ordinarily it takes a year 
and exceptionally it may take two years.] Naturally the length of the 
life-cycle is greatly dependent upon temperature, warmth accelerating 
metamorphosis and cold greatly retarding it as is shown by the observa¬ 
tions here recorded. 
AMBLYOMMA VARIEGATUM. 
The ticks to which the following record relates were (N. 1650) 
collected as gorged nymphs from cattle in the Lower Congo, 23-30. iv. 
1912, and they arrived in Cambridge in June, most of the adults having 
already emerged from the nymphal skins during the journey. 
