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plants. As filter-paper absorbs water, a similar roll of filter-paper was placed in 

 the jar, containing the non-etherized control-plants. The amount of the ether-dose 

 is stated in c. c. per liter air; furthermore the absolute quantity of ether is stated 

 together with the weight of the plant-material, used in the experiments, as it is neces- 

 sary to know these quantities in order to obtain some idea of the amount of the 

 dose used. Not until we know the relation between the amounts of ether which 

 are absorbed by the plants and by the air are we able to determine how much 

 ether the plants absorb, before equilibrium is reached between the pressure of the 

 ether vapours in the plants and that in the air; but it is easily seen that the 

 bigger the jar used the larger the dose of ether, in spite of the ether dose being 

 determined uniformly per liter air. When the portions used in the experiment 

 were large, or when the plants remained in a nutrient saline solution during the 

 exposure to ether, the amount of water has been taken into consideration at the 

 estimation of the amount of ether, that has been added, the relation between the 

 amounts of ether absorbed by water and by air being 22 [cfr. Johannsen 1906 p. 20]. 

 To demonstrate 'the effect of ether on the respiration estimations were made 

 of the carbon-dioxide, produced by plants, exposed partly to an atmosphere free 

 from ether, partly to an atmosphere containing a small or large dose of ether. 

 For this purpose was used the following apparatus, arranged by Johannsen [Johann- 

 sen 1897, p. 26]. Each set of plants was placed in an aspirator flask closed by 

 two rubber-corks, each pierced with a hole and fitted with glass tubes, connected 

 with short pieces of india-rubber tubes, which were closed by clamps. To estimate 

 the quantity of the carbon dioxide, accumulated in the jar through the respiration 

 of the experimental objects, a stream of air was sucked through the flask; the air, 

 admitted to the jar, was made free from CO^ by passing through two washing 

 bottles, connected with the above mentioned jar, the first one containing a strong 

 solution of KHO and the second one baryta-water, which served to demonstrate 

 that no extraneous CO2 entered the jar, containing the plants. Having passed the 

 jar the air was sucked through three Fresenius washing-bottles connected with 

 the jar, each containing 10 c. c. 15 p. c. of KHO, in which the absorption of the 

 COo, produced by the respiratory process, took place. The current of air was 

 drawn through the apparatus by an aspirator with a rapidity of c. 20 litres per 

 hour. In this manner a current of air was daily drawn through the apparatus 

 for 3 hours, a length of time which proved by experiments to be sufficient for a 

 complete discharge of the CO^, produced by the plants. Then the flask with the 

 plants was closed with the above mentioned clamps, the dose of ether renewed, 

 the plants remaining so in the flask till the next day, when the discharge of CO2 

 was again accomplished. The estimation of the quantity of CO2 produced was 

 made by titration of the KHO in the Fresenius washing-bottles. The following 

 method was used: Through the bulbed tube of the washing-bottle c. 30 cc. of a 5 

 per cent solution of BaCl.^ 2 H2O was injected with a pipette, by which process 

 all KHO was removed from the tube. The white mixture was transferred through 



