Scrub 
But these perfumes are really poisons, not only to 
animals but sometimes to insects. 
A West African Ocimum (basil) was tried as a cure 
for mosquitoes, and it was proved after careful investiga- 
tion (1) that mosquitoes were indifferent to its smell ; 
(2) that, if burnt in large quantities in a small room, 
neither a mosquito nor any human being could endure 
the smoke of it.6 Both fungi and parasitic insects are 
able to adapt themselves to all sorts of poisonous secre- 
tions, but those strong-smelling Labiates and others are 
certainly partially protected by these oils and resins. 
There has been a great deal of doubt as to whether 
such perfumes (that is, ethereal vapours) form a sort 
of vapour-screen round a plant and so prevent the 
escape of water, for if so they would be decidedly useful 
in a dry climate. In very hot still weather they surely 
must be of some use, but they can hardly be of very 
great importance.® 
The poisonous character of such oils on vegetable 
protoplasm has been carefully tested. When placed 
under a bell-glass so that the atmosphere became 
saturated with their own scented exhalation, pepper- 
mints poisoned themselves in eleven days, camphor 
plants in fifteen days, and Dictamnus in fifteen days. 
But if the air in the bell-glass is artificially saturated 
with their own vapours, lavender dies in 140 hours, 
and Mentha piperita in 74 hours.’ 
It is the strong scented breezes that are wafted from 
the maqui of Corsica which Napoleon in Elba re- 
membered whenever he shut his eyes. This maqui of 
thick and dense Erica arborea, mastic, shrubby oaks, 
&c., covers hills and valleys and for square miles 
together. Even to-day it is almost true that a brigand 
has only to take five steps into the maqui and 500 
gendarmes will never be able to discover him. This 
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