292 
Tick Paralysis 
Appendix I. 
I append the following notes upon the biology of D. venustus, since 
they bear directly upon the subject of this paper, and I have successfully 
I’aised the species from the affected locality. 
Protocols. 
Date 
25 VI. 
18 VII. 
22 VII. 
27-29 viL 
29 VIII. 
6 VI. 
12 vn. 
12 VII. 
24 IX. 
28 IX. 
5 XI. 
22 XI. 
28-30 XI 
20 II.-4 III. 1913. 
Lot I (1912). 
Gorged larvae of D. venustus were collected from a squirrel at 
Merritt, B.C. They were taken to the laboratory at Agassiz, 
placed in tubes with moistened filter paper, and kept at room 
temperature. 
The first nymph emerged (metamorphosis lasted 23 days). 
Six nymphs were placed on a rabbit (3-4 days after ecdysis). 
Three gorged nymphs dropped oft' the host (two after five days, one 
after seven days). 
One s and two ? s emerged (metamorphosis to adult lasted 32 days). 
Lot II (1912-1913). 
Gorged ¥ s of D. venustus were collected by Dr Thomson at Keremeos, 
B.C., from horses imported from the United States. The ticks 
were forwarded to Agassiz. 
The ¥ s began to oviposit (pre-ovipositiou period eight days). 
Larvae emerged (metamorphosis from egg to larva lasted 36 days). 
Larvae were placed on a rabbit (34 days after ecdysis). 
16 gorged larvae dropped off the host (the period of parasitism lasting 
four days). 
10 nymphs emerged (metamorphosis from larva to nymph lasted 
38 days). 
46 nymphs were placed on a rabbit (17 days after ecdysis). 
Three gorged nymphs dropped off the host (the period of parasitism 
on the host lasting 7-8-9 days). 
One ¥ and two <? s emerged (metamorphosis from nymph to adult 
lasted 84-94 days in a cold room). 
Note. These raising experiments were conducted at room temperature ; the tem¬ 
perature varied greatly, according to the weather, and in Lot II the metamorphosis of the 
adults was no doubt much prolonged. 
Copulation. 
The copulation of Dermacentor venustus was observed on a lamb’s 
back at Agassiz, British Columbia, on the 24th April, 1913. The act 
of copulation lasted 33 minutes. The operation began by the male 
hooking his three posterior pairs of legs under those of the female, then 
by his rooting about and inserting his hypostome into the vulva. The 
