FIELD CROPS. 331 



ical changes affect plant successions, but of necessity they are very slow in 

 their action. 



Mineral content of the leaves of fruit trees, L. Richter (Landw. Vers. Stat., 

 73 (1910), No. 6, pp. 457-478). — As a contribution to the autumn translocation 

 of mineral materials the author gives the results of a study of the mineral con- 

 tent of the leaves of the apple, pear, cherry, and plum at different stages of 

 growth, and of comparisons of the ash content of leaves and flower buds. 



Comparing the leaf and flower buds of the cherry and plum, the water con- 

 tent of the flower buds was found to be higher than that of the leaf buds, while 

 in the dry substance the flower buds were poorer in lime and phosphoric acid 

 than the leaf buds. Nitrogen and potash were similarly distributed, although 

 the differences were not so marked. 



In regard to the autumn changes, samples of 100 leaves each of the different 

 species were analyzed at intervals of about .3 weeks, covering the growing 

 period. The proportion of nitrogen to total dry substance was found gradually 

 to diminish from the period of its maximum, which varied in different species, 

 until the last period, when the loss was quite marked. A similar translocation 

 of phosphoric acid was noted. The potash content was almost constant, 

 although it diminished considerably during the later stages of growth. The 

 lime content increased until nearly the end of the growing period, when there 

 was a similar falling off. The ash content of all leaves except the plum was 

 fairly constant during the second stage of growth, but during the time that 

 elapsed between the last two samplings there was a decided falling off. 



The author claims there is a decided relation between the weather and 

 translocation. If warm weather continues well into the autumn much of the 

 mineral material of the leaves will be translocated, but if a sudden early fall 

 in temperature occurs the leaves are liable to drop from the trees before 

 translocation can be effected. 



Amount of copper in tea sprayed with Bordeaux mixture, H. E. Annett 

 and S. C. Kar (Jour. Agr. 8cl., 3 (1910), No. 3, pp. 3Vi-316).— Tests for the 

 presence of copper in unsprayed tea and that sprayed with Bordeaux mixture 

 showed that the unsprayed tea contained ttj gr. per pound, while the sprayed 

 tea contained * gr. per pound. Tests were also made of the infusion from 36 

 gm. of sjirayed tea leaves, and showed that if one drank as much as S cupfuls, 

 only an inappreciable amount of copper (0.0002 gr.) would be taken into the 

 system. 



FIELD CROPS. 



The electrification of crops, J. W. Robertson (Field [London], 116 (1910), 

 Nos. 3012, p. 516; 3013, p. 622; SOU, p. 665; 3015, p. 709, figs. 13).— In this 

 series of articles the author has gathered together the results obtained in 

 various countries in investigations of the influence of electricity upon growing 

 crops. 



J. E. Newman could discover no effect on strawberries at Evesham, but the 

 entire field was abnormal and yielded 4 tons per acre of jam fruit. A wire 

 run down the middle of a greenhouse and not more than 3 ft. from the straw- 

 berries apparently caused a marked improvement of the electrified fruit, the 

 crop being sweeter though not heavier. Both English and German investigators 

 are quoted as finding that electrification increases the sugar content of the 

 sugar beet. Mr. Newman reports in his work with wheat that " the result last 

 year was a difference between 30 and 36i bu. per acre. In Scotland last year 

 barley gave a small increase in the grain. . . . They have had a very dry season 

 indeed in Scotland until a fortnight ago, and when I walked over the oats I 

 could not see that there was any advantage gained by the electrified plats this 



