Pretreatment of intact hazel (Corylus avellana L.) seed with either ethanol or mercuric chloride alone is without effect in stimulating subsequent germination of seeds in the light. However, when treated with ethanol then soaked in mercuric chloride solution, intact seeds germinate when subsequently sown in light. Treatment with ethanol and mercuric chloride does not replace the light-requirement of intact seeds. The effect of such treatment is similar to that of removal of the testa. Ethanol may be replaced by diethylether, chloroform or n-propanol.