442 
Biology of Ixodidae 
Date 
26. X. 1912 
26. XI. 1912 
No. of gorged nymphs 
which dropped off host 
Day 
on successive days 
19 
2 
20-21 
3 
22 
27 
23 
43 
24 
9 
25 
26 
26 
34 
27 
73 
28 
32 
29 
120 
30 
40 
31 
8 
32 
50 
33 
20 
34 
86 
35 
30 
36 
193 
37 
80 
38 
30 
39 
16 
40 
60 
41-42 
55 
43 
30 
44 
175 
45 
90 
46 
11 
47 
8 
48 
9 
49 
170 
50 
9 
Total 1539 
The great irregularities observed in the supposed period of parasitism 
in this experiment must be attributed to experimental error due to the 
unfed ticks lying in the folds of the bag or only proceeding to feed upon 
the host after they had wandered about for an undetermined period. 
I have drawn attention to this source of error in the introduction to 
Part I (pp. 72-73). The minimum periods are always most trustworthy 
because of this source of error. The* first gorged nymphs abandoned 
the host on the 19th day, larger numbers only after the 22nd day, so 
that bearing the source of error in mind, this record agrees with the 
previous one. 
