428 EXPERIMENT STATION EECORD. 



Variations in mineral composition of sap, leaves, and stems of the wild 

 grapevine and sugar maple tree, O. M. Shedd (f7. S. Dept. Agr., Jour. Agr. 

 Research, 5 (1915), l^^o. 12, pp. 529-542). — In continuation of previous investi- 

 gations (E. S. R., 27, p. 801), the author lias made further observations at the 

 Kentucky Experiment Station on the mineral content of the sap of the v\-ild 

 grapevine {Vitis cordifolia) and of two species of maple (Acer sacclianim and 

 A. saccliarinum) . These experiments were conducted during three years to 

 determine whether the mineral composition of the sap varied at the same time 

 in different parts of the plant, whether it varied during a single season at a cer- 

 tain point, and whether it varied during different years. 



There was found to be considerable variation in the composition of the sap 

 when collected at the same time from different points, and great variation when 

 collected from the same point on the vine at different times during the same 

 season. The widest variation in the sap composition was found when it was 

 collected from the same point on the main branches of the vine at the beginning 

 of the sap flow during; four successive years. Considerable variation was ob- 

 served to occur daily in the composition of the sap. the mineral constituents being 

 generally higher during the day, while the sap had a more uniform composition 

 during the night. Young leaves and stems of the grapevine were found to vary 

 considerably during different years and also in the same season. 



The observations on the maple trees showed the sap to vary widely in com- 

 position when collected at the same point on the tree during two successive years 

 just after the s.ap flow had begun. The mineral composition of the two species 

 of maple was found to be quite different. It is thought that differences in the 

 composition of the sap can not be entirely explained as being due to a dilution 

 from the water in the soil, and it is believed that the variable mineral compo- 

 sition inlluences the structure of the gi'owing parts and explains the differences 

 in composition of the same and different varieties of plants. 



Boron — its absorption and distribution in plants and its effect on growth, 



F. C. Cook {Ahs. in Science, n. ser., J,2 (1915), No. 1096, pp. 951, 952). — On 

 account of the use of boron as a larvicide. experiments were conducted to de- 

 termine its effect on plant growth. 



This element is found to be readily absorbed by plants, and the addition of 

 lime to manure which had boon treated with borax had no definite effect on 

 the absorption of boron. Potatoes, string beans, soy beans, and co\\Te{is showed 

 a more equal distribution of boron in the roots, tops, and fruit than was the case 

 with wheat, beets, tomatoes, radi-shes, and lettuce plants. In some cases, very 

 little boron was found in the roots or fruit, while a considerable amount was 

 found in the rest of the plant. All control plants contained at least a trace of 

 boron. If sufliciont boron was added to the soil, a yellov.ing of the leaves took 

 place, but this was not considered to indicate that the yield would necessarily 

 be affected. Leguminous plants were found more sentitive to boron than any 

 other plants tested. 



Plant enzyms. — III, Pathological alterations in the amylase of potatoes, 



G. DoBY and J. BodnAr {Biochcin. Ztschr.. 6S (1915), No. 3-4, pp. 191-205; 

 ahs. in Jour. Chem. Soc. [London'}, 108 (1915), No. 630, I, p. 202).— In connection 

 with work previously reported (E. S. R., 28. p. 150), the author has studied the 

 changes in amylase concentration during the resting period of the potato tubers, 

 the changes in activity of the expressed sap, and the relation of amylase concen- 

 tration to potato variety and region where grown and to the health of the tubers. 

 The results are tabulated for each phase of the work. 



It appears that in juices of healthy plants the amyloclastic activity is greater 

 than in those from plants showing the presence of curly leaf disease. 



