328 EXPERIMENT STATION EECOED. 



In conclusion the author takes exception to the hypothesis that all inorganic 

 plant poisons act as stimulants when they are present in very small quantities. 

 She thinks a more accurate statement would be that some inorganic poisons act 

 as stimulants when in small amounts, the stimulating concentrations varying 

 with the poisons used and the plants on which they act. 



A bibliography is appended. 



Toxic effect of iron and aluminum salts on clover seedling-s, R. W. 

 RuPEECHT (Massachusetts Sta. Bill. 161 {1915), pp. 125-129, pi. i).— The author 

 claims that either iron or aluminum sulphate is harmful to the roots of clover 

 plants, even in dilute solutions. This toxicity is overcome in large measure by 

 the use of calcium carbonate up to a certain point, beyond which it is ineffective. 

 Calcium sulphate does not have this beneficial effect, which would seem to 

 indicate that it is the combination involved, and not the mere presence of the 

 calcium, which is here effective. 



Calcium carbonate counteracts iron and aluminum by precipitating them as 

 hydroxids. The toxic action of the hit:Cher concentrations of iron and alumi- 

 num, despite the excess of calcium carbonate present, is thought to be due to the 

 solubility of the iron hydroxid. 



The idea that the toxicity of iron and aluminum salts is due to the penetra- 

 tion of the salts into the seedlings does not seem to be borne out. Evidence is 

 offered in favor of the view that the toxic action is limited to the first layer or 

 two of the cells in the growing portion of the root. The final death of the 

 seedlings is due to a lack of nourishment rather than to a poisoning of the 

 seedling itself. No appreciable increase in iron content is found in roots or 

 tops of clover plants showing poor growth attributed to the influence of iron. 



Effect of salicylic aldehyde on plants in soil and solution cultures, J. J. 

 Skinner {Biochem. Bui., 3 (1914), No. 11-12, pp. 390-402, pis. 2).— On account 

 of the reporte<l presence of salicylic aldehyde in agricultural soils (E. S. R., 28, 

 p. 418), the author has conducted experiments with various plants in solution 

 cultures and in soil in pots. In addition the action of this substance, it is 

 said, is being tested with various crops in the field. 



Wheat, corn, cowpeas, cabbage, and rice have been tested in solution cul- 

 tures, and wheat, corn, clover in soil cultures, and it was foimd that salicylic 

 aldehyde was harmful to wheat and rice seedlings in distilled water, and to 

 all the crops tested in nutrient solutions and in soil in pots. The effect of 

 solution cultures with various fertilizer ingredients was also tested with wheat, 

 and it was found that in amounts as small as 10 parts per million, salicylic 

 aldehyde was injurious to its growth. The effect of this substance on the 

 absorption of nutrient salts indicatetl that there was a more nearly normal 

 absorption of phosphate than of nitrate or jjotash under the influence of salicylic 

 aldehyde. In tlie presence of calcium carbonate the injurious influence was 

 somewhat ameliorated. Experiments show that under alkaline conditions the 

 harmfulness of salicylic aldehyde can not be attributed to any slight acidity 

 it may possess. 



On the decrease of permeability due to certain bivalent cations, W. J. Y. 

 OsTERHOUT (Bot. Gaz., 59 (1915), No. 4, pp. 317-330. figs. 11).— It is stated that 

 while sodium chlorid and other salts of monovalent metals increase the per- 

 meability of protoplasm, calcium chlorid has the o])posite effect. This effect, 

 however, is not permanent. If exposure is sufliciently prolonged, it will be 

 found that it gradually passes away and is followed by increase of permea- 

 bility. The question of the behavior of other bivalent cations has arisen, and 

 the author investigated the action of a number of them on living tissues of 

 Landnaria saocharina. 



