The object in view has been to ascertain the intensity of assimilation in certain typical forest-plants, viz. Oxalis Acetosella, Stellaria nemorum, Melandrium rubrum, and Circea alpina, under different lights and supplies of CO2, and at the same time to examine the conditions of light, the CO2 concentration, and the temperature of the habitats, in order to arrive at an idea of the production of organic substance under the natural conditions. In addition to the forest-plants, a typical shore-plant, Nasturlium palustre, was also more closely examined. The estimations of the assimilation were carried out by means of a new apparatus constructed for ecological use. The principle of this apparatus is that the assimilation-chamber also constitutes an absorption vessel for the carbon dioxide, which is estimated over a baryta solution with a wide surface. The same apparatus was used for the estimation of the respiration and of the carbon dioxide of the air. For purposes of comparison the usual method with an air-current and absorption in a Pettenkofer tube was also employed.
