BOTANY. 335 



the boxes after the plants had attained a suitable size. Gravity cells were used in 

 all eases except in experiments with the interrupted induced current, in which case 

 sal-ammoniac cells were employed. 



The different experiments arc described at length, and with the radishes the 

 results of treatment with various kinds and strengths of current are shown, 3,446 

 treated and 2,022 untreated radish plants being compared. The comparisons are 

 based on the growth of the normal plants in each case and not on the total normal, 

 since the duration of the different experiments did not entirely correspond. The 

 results show appreciable gains and the percentages given represent a total gain for 

 roots and tops of 27.34 per cent due to the influence of electric treatment. The 

 growth of the tops showed a notable acceleration, being about 2.5 times as great as 

 the increased growth shown by the roots. 



The experiments with lettuce were somewhat similar in result, the increased 

 growth being slightly higher than the average percentage given for radishes, although 

 the acceleration was not as great as that shown in the growth of the radish tops over 

 the roots. 



The author concludes from the experiments that electricity has an accelerating 

 effect on the growth of plants as shown by the positive results obtained in hundreds 

 of experiments, and that the alternating current is much superior to the direct cur- 

 rent as a stimulator of growth. A discussion is given of the manner in which elec- 

 tricity stimulates plants, a number of theories being presented. 



The influence of the atmospherical electrical potential on plants, X. F. 

 MoN.vnAX (Massachusetts Sta. Rpt. 1903, pp. 31-36, fig. 1). — A brief account is given 

 of some preliminary experiments made to test the effect of atmospheric electrical 

 potential on germination, growth, and development of plants. The experiments 

 were conducted in large glass cases provided with doors fitted with rubber bands and 

 closed so as to render them practically air-tight. The stands were insulated and 

 arrangements made for determining the potential at any time. The cases in some 

 instances were charged with Holtz induction machines and at other times from Ley- 

 den jars, and the growth of the plants was measured by a self-registering auxomete 

 or by the use of horizontal microscopes. 



Experiments were carried on with seeds of white clover, onion, lettuce, red clover, 

 and muskmelon, and the effect on plant growth was studied with tomato plants, corn 

 cotyledons, and a number of molds. It was found that the atmospheric electricity 

 exerted a considerable influence on the germination of seeds, but did not increase to any 

 appreciable degree the total germination, nor did it awaken the activity of seeds 

 which had practically lost vitality due to age. Atmospheric electricity was shown 

 to have an appreciable influence on the growth of plants, and it is believed that 

 there is a maximum, minimum, and optimum potential which has not yet been 

 determined. The voltage required for the maximum, optimum, and minimum is 

 found to vary not only with different varieties or species of plants, but with different 

 individuals of the same variety, depending upon the size, degree of development, etc. 



The carbon nutrition of some plants by means of organic compounds, J. 

 Laurent (Rev. Gin. Bot, 16 (1904), No*. 181, pp. 14-48; 182, pp. 66-80; 183, pp. 

 96-128; 184, pp. 155-166; 185, pp. 188-202; 186, pp. 231-241, pis. 7).— After a' histor- 

 ical summary of investigations relating to the possibility of chlorophyll-bearing 

 plants assimilating carbon through their roots when grown in cultures containing 

 organic compounds, the author gives the results of a prolonged series of experiments 

 along this line. The plants experimented with were wheat, maize, buckwheat, peas, 

 2 varieties of beans, and the common groundsel. 



In order to obtain comparable results and to eliminate a source of error, all the 

 seeds were sterilized before germination and their roots were protected against infec- 

 tion by bacteria, molds, etc. The seedlings were grown in Knop's and Detmer's 

 solutions to which were added definite quantities of glucose, soluble starch, dextrin, 

 saccharose, glycerin, and humus compounds. 



