BOTANY. 227 



Jahrh., .3^i {W03), No. S, pp. 437-448, plx. ;?).— The rt'sults of experiinent.s with dif- 

 ferent substances, iiichiding rubidium chlorid, sulphate of manganese, uranium 

 nitrate, sodium fluorid, calcium iodid and iron sulphate, as stimulants of i^lant 

 growth, are reported. The experiments were made with barley, rice, peas, oats, 

 Brassica chiiiensis, and radishes, grown in pots and in the field. The data show that 

 these substances have a stimulating effect, and the author believes this to be of value 

 in agricultural practice, but states that through an accumulation of the same in the 

 soil their influence becomes injurious. 



The toxic eiFect of H and OH ions on seedlings of Indian corn, F. A. Loew 

 {tScicnce, n. ser., IS {1903), No. 453, pp. 304-308). — ^According to the author, attempts 

 have been made within the past 5 years to determine the toxic effect of various 

 chemical solutions upon plant life. This involved the theory of ionization and is 

 based upon the electrical conductivity of the solutions. After discussing some of 

 the theories and previous investigations, the author gives an account of experiments 

 in which the effect of these various dilutions of potassium hydroxid, sodium 

 hydroxid, hydrochloric and sulphuric acid on seedlings of Indian corn was tested. 



The test solutions were made in 4 different dilutions, and, after germinating the corn, 

 the sprouted grains were placed in test glasses in such a way that the radicle was held 

 in contact with the solution. The seedlings were then kept in a dark chamber for 

 24 hours, after which the growth or elongation was noted. The results obtained by 

 the different experiments are shown in tabular form, from which it appears that the 

 corn seedling lived and grew in a 1/128 normal solution of the alkalis and 1/512 nor- 

 mal solution of the acids. This shows that corn seedlings live in an alkali solution 

 more than 3 times as strong and an acid solution 12 times as strong as that in which 

 the seedlings of white lujiine live, as previously reported (E. 8. R., 11, p. 1100). 



The physiological r61e of mineral nutrients in plants, O. Loew ( U. S. Dept. 

 Ar/r., Bureau of Plant Indnstrij Bui. 45, x>P- 70. ) — This is a revised edition of Bulletin 

 No. 18 of the Division of Vegetable Physiology and Pathology (E. S. R., 11, p. 1008), 

 with some additions. The following is added to the final remarks: 



"A question of considerable importance for agriculture is the judicial regulation of 

 the lime and magnesia content of the soil, especially when mineral fertilizers are 

 employed. This regulation must be based on the knowledge of the readily assimi- 

 lated amounts of these bases. Hence only the finer soil particles should serve for 

 analysis^ When a soil is much richer in magnesia than in lime extensive liming is 

 necessary. The liming should be done chiefly with the carbonate and only in part 

 with slaked lime and the sulphate. On the other hand, when the magnesia content 

 is much less than that of lime the addition of a powdered magnesian limestone or 

 magnesite is necessary. Burned magnesite and artificially precipitated magnesium 

 carbonate must be avoided under all circumstances, since they are too finely divided 

 and too easily absorbed." 



Experiments by May (E. S. R., 13, p. 630) and by Aso and Furuta (E. S. R., 14, p. 

 14) are cited as having shown that "cereals thrive best when the lime content of the 

 soil only slightly exceeds that of magnesia. Crops having more abundant foliage, 

 however, require considerably more lime. For the most luxuriant development cab- 

 bage needs twice as much lime as magnesia, while buckwheat requires three times as 

 much lime as magnesia." 



Bacteria and the nitrogen problem, G. T. Moore {V. >S. Dept. Ayr. Yearbook 

 1902, pp. 333-342, ph. 6). — A review is given of the importance of nitrogen for plant 

 growth and the different sources from which nitrogen is obtained. The assimilation 

 of nitrogen through the root tubercle organisms which are found on the roots of 

 many leguminous plants is discussed, and the results of investigations on the culti- 

 vation of this organism for artificial inoculations are briefly described. 



The author found that the bacteria could be made to grow on media which did 

 not contain any of the decoctions of the host plant, such as are used in the ( Jerman 



