G. H. F. Nuttau. 
441 
Date 
7. XI. 1911 
27. XI. I'Jll 
Day 
No. of gorged nymphs 
wliich dropped off host 
on successive days 
Remarks 
20 
1 
Larvae are fully gorged about 
21 
09 
the 8th day; the nymphs 
22 
312 
emerge about the 12th day, 
23 
477 
and, reattaching themselves 
24 
476 
in situ upon the host, they 
25 
414 
proceed to suck blood and 
20 
150 
mostly drop off gorged on 
27 
32 
about the 22nd day. 
28 
32 
29 
103 
30 
15 
32 
18 
33 
20 
34 
3 
35 
6 
36 
4 
38 
0 
39 
8 
2152 
From this table it will he seen that a gorged nymph dropped oft' on 
the 20th day but that considerable numbers began to fall oft: onh^ on 
the 22nd day; those abandoning the host in large numbers on the 
24-26th day, are largely attributable to larvae placed on the ram on 
21. and 2.3. x. 1911, i.e. 2-4 days later than the first batch. 22 days 
can therefore be accepted as the period of parasitism for the great 
majority. Assuming that the last ticks to drop oft were those placed 
on the ram on 23. x. 1911, then the maximum period of parasitism may 
be reckoned at 36 days (not 39 days, as appears from the table). 
(Second generation.) 
Larvae (progeny of $ No. 2 raised in Cambridge) which emerged 
1. VII. 1912 were placed on a ram on 7. x. 1912, 98 days having elapsed 
since they emerged. The ram was maintained at an average temperature 
of 8-5° G. 
