[The hatching of the eggs of the liver fluke Fasciola hepatica L. under various CO2-concentrations (author's transl)].

The presupposition for the hatching of the eggs of Fasciola hepatica is the presence of undissociated CO2 with the most effective concentration of 2-10 mMols/l. Higher concentrations show inhibitory effects (Abb. 6). In hatching pH has only importance in dissociation of carbonic acid and so in maintaining free CO2. To provide for sufficient CO2 at higher pH - but below 8.3 - the concentration of carbonic acid must be increased by higher concentrations of metallic ions electrically neutralized by hydrogen carbonate (e.g. in Abb. 1-4). Higher pH is necessary for miracidia surviving. Beside the wellknown hatching factors of exposure to light and cooling, darkening is a new found factor (s. Abb. 7) as well as sufficient increase of CO2 itself. The effect of light stimulation is lasting for at most 3 h with exponential decrease (Abb. 7). At low CO2-pressure the occurrence of hatching is greater without any oxygen (Abb. 5).