548 EXPERIMENT STATION RECORD. 



the effect of colored lif^ht upon jflants, the author claims to have shown that red 

 ravs favor the development of most plants, and the exclusion of blue an<l green is 

 also favorable to their best growth. 



The influence of electricity upon plants, C. Flammarion [Ann. Min. Agr. 

 [France], 21 {1902) , No. 2, jij). 400, 401). — A report is given of experiments in which 

 beans were planted between copper and zinc plates buried in the ground and con- 

 nected with a Leclanche cell. The author has experimented with this form of appa- 

 ratus since 1894, and comparing the results finds considerable variation. The 

 contradictory results are attributed to different conditions of the atmosphere, 

 moisture, and temperature, all of which must be considered in similar experiments. 

 In general, however, the electric current exercised a stimulating effect on the growth 

 and production of the plants. 



Certain relations of plant growth to ionization of the soil, A. B. Plowman 

 {Amei: Jour. Sri, 4. ser., 14 {1902), No. SO, pp. 129-182).— A description is given of 

 a series of experiments on the relation of plants to electricity, conducted at the Har- 

 vard Botanic Garden. Among the facts recorded the author states that seeds placed 

 near the anode are always killed by currents amounting to 0.003 ampere or more if 

 continued for 20 hours or longer, while seeds placed near the cathode have in most 

 cases been but little affected and under some conditions stimulated by the currents. 

 When the seeds were germinated in water the difference was most pronounced when 

 a relatively heavy current was ])assed through the water for only a short time. In 

 this case the seeds near the anode were killed while those near the cathode were 

 apparently uninjured. These differences are attributed to the dissociation of the 

 atoms by the electric current. When seeds are germinated in distilled water through 

 which a weak current is forced, the oxygen ions are in excess in that part of the 

 solution wdiere the stimulation occurs, and the hydrogen ions are in excess where 

 the plants are killed. The different effects are believed to be produced by the elec- 

 trical charges of the ions rather than by any mere chemical activity of the atoms. 

 When seeds are placed in solutions of various acids, bases, or salts of a degree of 

 concentration far below the killing point, they will germinate as well as in ordinary 

 distilled water, but when a current of electricity of sufficient strength to propel the 

 ions is passed through the solution that part about the anode becomes destructive to 

 plant life. 



From these facts it is concluded that negative charges stimulate and positive 

 charges paralyze the embryonic protoplasm of plants. In support of this theory it 

 is shown that if a flower pot containing several lupines of about 4 weeks' growth is 

 charged with positive electricity the plants cease to grow, gradually lose their tur- 

 gidity, and finally die; while if the charge be negative these effects are not produced, 

 but the plants are stimulated. When seedlings are grown in an aqueous culture 

 medium through which a weak current of electricity is passed, the. root tips turn 

 toward the anode. Normally the plant body is electro-positive to the soil in which it 

 grows. The positive charge of the plant attracts the negative ions of the soil to its 

 roots, and any circumstance which would facilitate the electrical interchange would 

 be expected to be beneficial to the plant, as the reverse conditions would be detri- 

 mental. These phenomena are dependent not only upon temperature, light, aera- 

 tion, and moisture, but also upon the nature of the electric current used, degree of 

 dissociation, physical state of the ions, etc. 



Effect of the composition of soil on the minute structure of plants, H. B. 

 DoRNER {Froc. Indiana Acad. Sci. 1901, pp. 284-290, pU 2) .—The object of the experi- 

 ment reported was to determine whether the variations in soil produce other than 

 gross changes in plants. A number of well-known plants were grown in loam, clay, 

 and sand under otherwise identical conditions. The change in soil was found to 

 decrease the size of the plant, its leaf surface, length of petioles, diameter of the stem, 

 length of internodes, masses of roots, and to cause variation in color, the decrease 



