AGRICULTURAL BOTANY. 329 



Study of peas, maize, and beaus cultivated in dilute solutions of nitrate or 

 chlorid of barium are given, the experiments witli peas being described at con- 

 sidei'able extent. In these experiments, after germinating the peas in distilled 

 water they were placed iu solutions of barium, a strength of 0.125 per thousand 

 being found best suited to the purpose of the investigations. After growing the 

 plants for some time iu these solutions they were examined microchemically 

 and the amount of barium determined chemically. 



In the experiments with peas practically all the barium was found localized 

 in the roots, although there were traces to be found iu the stems of the plants. 



Relation of the salts of calcium, to the assimilation df nitrate nitrogen 

 by green plants, V. P. Ermakov {Univ. Izv. [Kiev], //S {1908), No. 5, Art. 3, 

 pp. 1-68; ahs. in Zliur. Opititii. Agroa. {Russ. Jour. Expt. Landiv.), 10 {1909), 

 No. 3, pp. 39^-396). — In a series of experiments leaves of a number of species 

 of plants were placed with their petioles in solutions of nitrates for a day or 

 two, after which they were examined microchemically for nitrates. An accumu- 

 lation of nitrates was observed only iu the leaves which had not received any 

 calcium. 



In another series of experiments leaves which had been previously placed in 

 solutions of potassium nitrate or sodium nitrate and had accumulated nitrates 

 were transferred into solutions containing calcium salts, when the nitrates 

 which had been accumulated by tlie leaves disappeared. From this the author 

 concludes that for the assimilation of nitric nitrogen the presence of calcium 

 salts is necessary. 



In addition to the microchemical examination, quantitative determinations 

 of nitric nitrogen in the leaves were made, and the analytical results corrobo- 

 rated those obtained microchemically. In the presence of calcium chlorid and 

 calcium sulphate the leaves of grapes and Paulownia were found to assimilate 

 more than 90 per cent of the accumulated nitrates, while in the absence of 

 these salts only from 10 to 15 per cent of the nitrogen was assimilated. 



Another series of experiments was conducted to determine the dependence 

 of the accumulation of organic nitrogen on the presence or absence of calcium, 

 comparing grape leaves placed for 24 hours in solutions of calcium nitrate and 

 potassium nitrate, potassium nitrate, potassium nitrate and calcium chlorid, 

 potassium nitrate and calcium sulphate, and potassium nitrate and potassium 

 sulphate. In each case 100 leaves were used, 50 receiving calcium, the others 

 not. All the experiments showed that in the plants receiving calcium, the 

 amount of organic nitrogen was increased on an average about 10 per cent, 

 while it remained unchanged in those receiving no calcium salt. 



The influence of a lack of lime on the seedlings of Phaseolus vulgaris, 

 DoKA Hoffmann {Osterr. Bot. Ztschr., 60 {1910), No. 2, pp. ()i-6-i).— Experi- 

 ments were conducted with bean seedlings the roots of which had been wounded 

 to test the effect of a lack of lime on the plants. The roots were entirely re- 

 moved or half their length cut off and the seedlings were then grown in distilled 

 water, spring water, a complete nutrient solution, and a similar solution with- 

 out lime. 



In the cultures grown in spring water and in the nutrient solution the roots 

 of all the plants remained sound, while in the distilled water and in the lime- 

 free solution they became diseased in from 5 to 11 days. In a similar manner 

 the aerial parts of the plants became diseased, those without any roots remain- 

 ing free from disease 1 or 2 days longer than those with intact roots. The 

 plants with half roots developed symptoms of disease about the same time or a 

 little later than those with sound roots. In general the injury to the aerial 

 portions of the seedlings due to a lack of lime was iu inverse proportion to the 

 root development. 



