232 
Culicifuges 
40 % . No. 17. 
43 %. No. 14. 
53 % . No. 20. 
62 % . No. 18. 
63 % . No. 19. 
2. Long Period Trials. 
Nos. 1 and 21. 
No. 2 a (combined result of two trials: A. B. shows 9 %. G. T. shows 39 %). 
No. 15 a. 
No. 9 a. 
No. 10. 
No. 5. 
No. 22 a. 
No. 15 a. 
No. 9 b. 
No. 1. 
XI. BEHAVIOUR OF THE MOSQUITO IN THE PRESENCE 
OF THE CULICIFUGE. 
In the cage the untreated arm is generally attacked by the insects after 
the lapse of not longer than.two minutes. A treated arm, where the prepara¬ 
tion used is not effective, is attacked within the same period. After a lapse 
of five minutes all the hungry females will have generally attacked. 
We noted, during the first series of tests (see Table I) that with effective 
preparations, the insects sometimes settled on the treated arm and walked 
over it, flying off again without feeding, being apparently indifferent to the 
odour. 
Again, with most of the preparations the wounds occurred on the wrist 
and towards the elbow, such localised attacks being possibly due to the 
proximity of the untreated areas of hand and arm. 
On one occasion, in applying a preparation, a narrow streak was inadver¬ 
tently left untreated, and the insects not only bit on that area, but also through 
the preparation in the area immediately adjacent, no bites being found elsewhere. 
Our observations therefore show that the preparations are only likely to 
be effective within a very restricted range. Moreover, the entire exposed 
area must be covered, and steps must be taken for renewed application, even 
with the best of the culicifuges experimented with, at intervals of not more 
than two hours. 
On the basis of these observations we are inclined to put forward a ten¬ 
tative theory to the effect that the action of the culicifuges is rather to 
obscure the human odour than to repel the insects. 
2 hours. 
28 %. 
29 %. 
33 %. 
38 % • 
42 %. 
49 %. 
56 %. 
3 hours. 
5 hours. 
71 % • 
