AGRICULTURAL BOTANY. 81 



to confirm the conclusions of Ac(iUa (E. S. R., 29, p. 323), which are to the effect 

 that the points of deposit of certain metallic ions in growing regions are also 

 points of utilization of the acid portions of the nutritive compounds involved. 



In case of wheat and beans the deposit of manganese occurred when this 

 cation was united with an indifferent or injurious anion, if nitrate in other and 

 harmless form was supplied to the plant, the rate and amount of manganese 

 deposit proving independent of nitrogen assimilation. The blackening was 

 independent of light admission and is probably explainable as related to enzy- 

 matic processes. The deposit of manganese dioxid in case of Elodea canadensis 

 occurred only in light and apparently was not due in this case to nitrogen 

 assimilation. The deposit of manganese failed only when the endodermis was 

 continuous and unwounded, or when the epidermis acted as a chemical filter. 

 On employment of low concentrations of toxic substances or of very concen- 

 trated nutritive media, the inner endodermis thickened in case of all plants 

 studied which possessed uninterrupted endodermis. Distilled water had the 

 same effect on the endodermis as did a weak poison, while various strong poisons 

 able to check growth caused no such thickening of endodermis. Potassium per- 

 manganate was reduced commonly in the outer layers of cells, otherwise always 

 in the third or fourth layer, never reaching the vascular bundle cylinder proper. 



The sig-nificance of deposits occurring in plants cultivated in solutions of 

 manganese salts, C. Acqua (Ann. Bot. [Rome], 11 {1913), No. S, pp. JidJ- 

 471). — This is a critical note in reply to the above article. 



On the presence of deposits in plant tissues due to culture in manganese 

 nitrate solution, Eva Boselli (Ann. Bot. [Rome], 11 {1913), No. 5, pp. 459- 

 465). — Results obtained from the study of 11 plants covering a wide range of 

 forms are said to confirm the conclusions arrived at by Acqua (E. S. R., 29, 

 p. 323), but to be at variance with those reached by Houtermans noted on 

 page 30. It is stated that a close relation appears to exist between the deposit 

 of cations and the changes occurring in newly formed tissue. 



The influence of calcium, magnesium, and potassium nitrates upon the 

 toxicity of certain heavy metals toward fungus spores, L. A. Hawkins 

 {Physiol. Researches, 1 {1913), No. 2, pp. 57-92, figs. 6).— The results of a study 

 of the influence of one salt in altering the toxic effect of another upon fungus 

 spores are given. The salts employed were the nitrates of copper, lead, zinc, 

 nickel, and aluminum used alone and in combination with the nitrates of 

 calcium, magnesium, and potassium. 



It was found that the effect of a toxic salt on the germination of the conidia 

 of Glomerella cingulata might be influenced by the addition to the medium of 

 calcium, magnesium, or potassium nitrate. This effect, it is claimed, is not due 

 to a depression of ionization of the toxic salt nor to the formation of undis- 

 sociated double salts, but the influence of calcium upon the toxicity of the salts 

 of the heavy metals employed is to be referred to an effect of the calcium 

 nitrate on the spore or on the contained protoplasm. 



A bibliography is appended. 



Experiments on the action of sodium sulphate as affecting growth of 

 plants, E. Haselhoff {Landw. Jahrb., 44 {1913), No. 4, pp. 641-650) .—Dis- 

 cussing the results of former investigations on the effect of flue dust (E. S. R., 

 19, p. 1130; 21, p. 128) and in connection therewith his more recent studies 

 regarding the action of sodium sulphate on growing beans, barley, and Indian 

 corn, the author claims that in spite of individual variations it is safe to con- 

 clude that sodium sulphate in 0.05 per cent strength, while sometimes hastening 

 development, usually decreases the total growth of the plants studied as esti- 

 mated by weight, the growth in length proving unreliable in this respect. The 

 soil-culture studies indicated an injurious effect of sodium sulphate on 



