314 
may not perceive when he is bitten. This is by no me ins uncom 
inon, especially when people are asleep, and I have known cases 
where two people were sleeping close together, and one complained 
that he could not sleep on account of the mosquitoes, while the other 
said he did not notice them. Secondly mosquitoes may be absent 
or verv few in number, and their absence may be attributed to the 
presence of the basil plants. It was necessary, therefore to devise 
some means of excluding the personal dement, and it appeared to 
me that if two specially constructed cases were placed at some dis- 
tance from each other, with free communication between them, 
these requirements would be met. Accordingly I had two ca>es 
made, three sides of which were covered with mosquito net, and the 
fourth was solid. In this side a large circular opening was made. 
The cases were placed with the solid sides facing each other, and 
the openings were connected with a short tube of mosquito netting. 
Along this tube it was found the mosquitoes would fly easily. I 
attach an account of the experiments in detiil for reference, but 
here I content myself with epitomising the details. 
The mosquitoes used were bred out fro m larvae and consisted 
mainly of Stegomyia, the most common mosqu'to in Freetown but 
there were also a. few Anophzles and Culices. 
In one case (called No. i) two large basil plants (about 18 indies 
hicrh) were placed, along with some ripe bananas as food for the 
mosquitoes. In the other case (No. 2) only bananas were placed 
so as to equalise the conditions as regards food. On the 3 r; i June, 
eleven mosquitoes were liberated in case No. 1. They showed no 
' discomfort and an hour afterwards were found perched on the roof 
and sides of the case. On the morning of the 4th seven were 
counted incase I, one was in the tube and none incise No. 2. 
Two free mosquitoes were found perched on the outside of the 
netting of case No. I (containing the plants). This is a very im- 
portant observation as showing that, although there was a large 
room to perch in, the attraction of the food overcame the antipathy 
to the basil-plant. On the 5th one only was found in case No. 2, 
the rest in case No. 1. On the 6th the same condition was found 
and the experiment was concluded, it may be mentioned here that 
in all the experiments the number of mosquitoes gradually dimin- 
ished owing to their dying. In some cases the dead bodies were 
found, in others they were eaten by small ants. Here, therefore, 
it was clearly shown that mosquitoes would remain in close proxi- 
mity to basil plants although there was a free way of escape, and a 
supply of food accessible elsewhere. I repeated the experiments 
a second time with similar results. On this occasion one mos- 
quito settled on a leaf and remained there for some minutes, and 
on the following day two were perched on the stem of the plant tor 
over an hour. A free mosquito was found on the netting outside 
the case. Several mosquitoes were observed perched on the wall 
of rooms at distances varying from six to twelve feet from the basil 
plants. 
In the third experiment the conditions were altered. Three pots 
