Good results may be obtained by combining all these methods. When the tissues are reasonably free from air the specimens should be placed in a dilute (5 per cent.) glycerol solution containing enough dissolved copper sulphate or copper acetate to give it a marked bluish tint. The solution should be boiled before using to free it from air. At the time of using, enough formalin should be added to make the solution about i per cent. The specimens should be left in this until all of the green parts have been penetrated by the copper and have assumed a bluish green color. They should then be removed to a dilute glycerin-formalin solution free from copper. This will gradually dissolve all the copper not in combination with chlorophyll and thus bring out the natural shades and variations. After thorough washing and clearing in this latter solution the material may be preserved, without change, in glycerin-formalin solution or any of the common media except strong alcohol.