AGRICULTUKAL BOTANY. 31 



increase in dry weight 17 mg. per square decimeter per liour, the catalpa leaves 

 showed an increase of only 5 or 6 mg. 



These results were obtained with detached leaves of the plants, and it remains 

 to be determined whether leaves still attached to the plants assimilate at 

 equally high rates. 



Attention is called to the experiments of Brooclcs with sugar beets, which 

 proved that translocation proceeds during the day. 



The author hopes to carry on some experiments to obtain conclusive evidence 

 as to the concurrent action of assimilation and translocation. 



On the absorption of water by tlie seeds of Vicia faba, A. S. Horne and 

 Susanna Coull (Proc. Univ. Durham Phil. Hoc, 3 (1909-10), No. 5, pp. 267-280, 

 pi. 1, dgms. 6). — Attention is called to the trough-like organ present in the hilar 

 region of the testa of leguminous seeds, and some experiments are reported in 

 which the role of this organ in water absorption was tested. 



The author found that a considerable portion of water was absorbed directly 

 through the testa of the seeds of V. faha, the curves of the unsealed seeds and 

 those having the hilum and micropyle covered with wax being almost parallel. 

 With leguminous seeds having as permeable a testa as the broad bean, it is 

 probable that the scar plays an inconsiderable role in the direct absorption of 

 water, although with seeds having a less permeable testa it may be of some 

 importance. 



The presence of a glucosid in the leaves of the pear, E. Botikquelot and 

 Mile. A. FiCHTENHOLz {Compt. Rend. Acad. Sci. [Paris], 151 (1910), No. 1, pp. 

 81-S4)- — The authors report the occurrence in the fresh leaves of several varie- 

 ties of pear of a glucosid which from their studies is believed to be arbutin. 



Starch content of leaves dropped in autumn, L. L. Harter (Ahs. in Science, 

 n. ser., 32 (1910), No. 816, p. 256). — The author reports finding from 6 to 14 

 per cent of starch in dropped leaves of Liquidambar, Ginkgo, Styrax, and oaks, a 

 fact which seems to indicate that all food materials in leaves do not undergo 

 translocation in autunni, as is commonly believed. 



The influence of copper sulphate and mang'anese sulphate upon the growth 

 of barley, Miss W. E. Brenchley (Ann. Bot. [TAmdon]. 2Ji (1910), No. 95, pp. 

 511-583, pi. 1, dgms. 4). — The author has carried on a series of experiments to 

 test the theory that chemical substances which are deleterious to plant growth 

 universally act as stimulative agents if available in exceedingly minute quanti- 

 ties. The experiments were carried on with barley germinated and then trans- 

 ferred to water cultures containing various dilutions of copper sulphate and 

 manganese sulphate. 



The action of plant poisons in dilute solutions was found to be masked by the 

 presence of nutrient salts, which enable the plants grown in such solutions as 

 water cultures to endure a much greater concentration of the toxic substance 

 than in the absence of nutrients. 



Copper sulphate, which was found to be a definite poison to barley, does not 

 have any stimulative effect in very dilute solutions, even at as low a concentra- 

 tion as 1 part copper sulphate to 10,000,000. Manganese sulphate, though not 

 an actual poison to barley, retards the growth very materially if supplied in 

 moderate quantities. Minute traces of the salt had a decided stimulative action 

 both on the roots and shoots. When supplied in sufficient concentration the 

 manganese was found to be taken up by the plant and deposited in its lower 

 leaves. 



On the toxicity of certain salts toward green leaves, L. Maquenne and E. 

 Demoussy (Compt. Rend. Acad. 8ci. [Paris], 151 (1910), No. 3, pp. 178-182).— 

 The authors describe a method of determining the toxicity of salts toward 

 plants in which leaves are floated in the solutions and the blackening of the 



