318 EXPERIMENT STATION RECORD. 



Movement in plants, F. Darwin (Rpt. Brit. Assoc. Adv. ScL, 190S, pp. 

 3-27). — This is the presidential address delivered before the British Association 

 and describes the author's investigations and conclusions regarding the power 

 of movement in plants. 



The influence of pulling tension on tlie formation of mechanical tissue in 

 the stems of plants, J. S. Bordner (Rpt. Mich. Acad. 8ci., 10 {190S), p. JfS). — 

 A brief account is given of experiments conducted to determine the effect of 

 pulling tension along the longitudinal axes' of plants. One hundred and thirty- 

 hve stems were subjected to tension and an anatomical study afterwards made 

 of them. The tension was applied by means of weights suspended from cords 

 running over light pulleys. 



The results obtained with sunflowers, nuistard, beans, castor beans, etc., showed 

 an increase in the breaking strength of from 5 to 55 per cent. This was accom- 

 panied by an increase of xylem or of hard bast and in most species of both. 

 In the case of the blackberry {Ruhus occidentalis) there was an increase in the 

 hard bast but a decrease of xylem in the experimental iilants. 



The influence of contact and tension upon the tendrils of Passiflora coerulea, 

 W. D. Brush (Rpt. Mich. Acad. Sci., 10 (1908). p. -f'/).— A brief sketch is given 

 of experimental work carried on by the author during two years to determine 

 the effect of contact and tension upon the strength of tendrils. The results 

 show that contact had a marked effe-ct in producing greater strength of the 

 tendril, and important anatomical differences were found in tendrils due to 

 contact and 1o tension. 



Effect of swaying' by the wind on the formation of mechanical tissue, 

 Maude Gilchrist (Rpt. Mich. Acad. !Sci., 10 (1908), p. -'/o). — Experiments are 

 reported with the common garden sunflower to show the effect of swaying mo- 

 tions on the development of mechanical tissue. These motions were obtained 

 by means of special apparatus operated by an electric motor. It was found 

 that the stems of plants swayed as by the wind are shorter and thicker than 

 those not swayed, the diameter in the plane of swaying is greater than that at 

 right angles, the xylem in the plane of swaying is increased In amount, the 

 rigidity of the stems is increased, and the tensile strength appears to be de- 

 creased, although the work on this point is not considered conclusive. 



The influence of living cells on the transpiration current, H. H. DixoN 

 (Rpt. Brit. Assoc. Adr. Sci., 1908, p. 901). — A brief account is given of some 

 investigations to determine the influence of living cells on the transpiration cur- 

 rent. Two similar branches were selected, one of which was killed by being 

 surrounded with steam, and the rates of transmission were observed in both 

 branches. The similarity of action of both branches indicates that the influence 

 of living cells on water transmission is insensible. Similar results were obtained 

 when branches were killed with picric acid. 



The fading of leaves due to want of water is held to be quite different from 

 the fading of those supported by dead cells. In the latter case there appear 

 indications of poison, and the poisonous effect of water which has passed 

 through a killed branch may be observed by supplying water to the basal leaves. 

 These experiments are held to lend no support to the vital theories of the 

 ascent of sap. 



On the increase in dry weight as a measure of assimilation, D. Thoday 

 (Rjjt. Brit. Assoc. Adv. Sci., 1908, pp. 905, 906). — The author has carried on 

 investigations on the method of determining the rate of assimilation from the 

 dry weight of plants, since that method appears to be the only one available 

 for determining the rate of assimilation in the open air. This method was 

 first suggested by Sachs in 1883, and the author's investigations show that 



