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Une souche deBacillus thuringiensisBerliner dite «Anduze» et isolee en 1952 dans une magnanerie des Cevennes a ete cultivee et preparee en vue de son utilisation comme moyen de lutte bacteriologique contre la Pieride du Chou,Pieris brassicaeL.

The researchs of different authors on the conditions of the pathogenous effect ofBacillus thuringiensis are rewied with special reference to the toxicity of the crystal bodies which appear during the sporulation. Pure extracts of crystal obtained by theAngus method were tested by the technic ofBurgerjon. Pure crystals are 2,5 times more active than the standard preparation ofB. thuringiensis. Spores from which the crystals are removed have no toxicity. The works ofHeimpel are discussed at the light of this study: to-day it appears that the toxemy is caused by the crystalline protein in the caterpillars with intestinal pH>9; other toxical possibility of the germ may appear by influence of others conditions.