India and China are also very large producers of essential oils.
It is to be noted that there is no fixed relation between toxin production and bacterial multiplication in the body, some of the organisms most active as toxin producers having comparatively little power of invading the tissues.
America has furnished European supplies since the discovery of the Potosi mines of Peru in 1 533; Bolivia and Chile are also notable producers.
Spain also supplies much pyrites to Germany, France and America, all of which countries are themselves producers of this ore.
As regards the mode of production of galls, the most important distinction is between galls that result from the introduction of an egg, or other matter, into the interior of the plant, and those that are due to an agent acting externally, the gall in the latter case frequently growing in such a manner as ultimately to enclose its producers.