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 (i) 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. 5 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. 6 



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. 7 



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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