2 With the assistance of this little apparatus the snuff-taker may himself provision his nostrils, but the large apparatus , each tube of which is more than six inches long, cannot be used without the help of a comrade, who introduces one of the tubes into each nostril of the snuff-taker in turn.
All these species, as the learned Humboldt has well observed, are confined to certain regions which they never leave, and which are so clearly defined, that a league before reaching the territory of the Conibos, one may pass the night under the sky without feeling a single zancudo, whilst the instant we set foot among those indigenes it is impossible to sleep without a mosquito-curtain.  2 With the assistance of this little apparatus the snuff-taker may himself provision his nostrils, but the large apparatus , each tube of which is more than six inches long, cannot be used without the help of a comrade, who introduces one of the tubes into each nostril of the snuff-taker in turn.  The operation is of course performed turn and turn about, and the active r&le of insuffleur is exchanged by each of the two individuals for the passive one of insuffle.