820 EXPERIMENT STATION RECORD. [Vol. 40 



stances. Both barium and strontium carbonates accelerated the growth of 

 roots of plants investigated. Increasing the amount of strontium nitrate 

 resulted in an increase of the nitrogen content of the wheat. No barium 

 compounds were found in the residue obtained upon evaporating 25 liters of 

 water collected from the drain tiles of the station farm, and this is considered 

 to indicate that the barium found" in plants is taken up in place by the plant 

 roots. 



The effect of manganese compounds on soils and plants, E. P. Deatrick 

 (New York Cornell Sta. Mem. 19 (1919), pp. 365-1,02). — The investigation here 

 reported was undertaken for the purpose of ascertaining the specific effect of 

 manganese compounds in increasing plant growth, that is, to determine 

 whether manganese is a direct plant stimulant, whether it increases the avail- 

 able food supply in the soil, or whether both of these factors are operative. 

 The experiments were carried out with wheat, the plants being grown in dis- 

 tilled water alone and in distilled water to which nutrient solutions were 

 added. 



It was found that manganese salts added to water cultures affected the 

 growth of wheat seedlings, high concentrations of both the sulphate and 

 chlorid exerting toxic effects, while in lower concentrations marked stimula- 

 tion was observed. The degree of toxicity was found to be reduced by full 

 nutrient solutions, the reduction being directly proportional to the cone, ti- 

 tration of the nutrient salts. The food stored in the endosperms was also 

 found to reduce the toxicity of the plant poison. The toxic intluence of tin- 

 salts was shown in the browning of the roots and the bleaching of the lea<^ 

 Yellow leaves of manganese plants contained more of that element than did 

 green ones. 



Manganese salts when added to soil were found to form manganese dlozld in 

 proportion to the basicity of the soil and thus to develop a power to oxidise 

 organic matter. Manganese sulphate in water cultures stimulated the oxidiz- 

 ing power of the rents of wheat seedlings. Low concentrations of manganese 

 sulphate were found to stimulate the ammonlfication of dried blood in the 

 soil. The nitrification of ammonium sulphate was Inhibited. 



Root variations induced by carbon dioxid gas additions to soil. H. A. 

 Notes, J. F. TaosT, and L. ToDKB (B&f. Cnz.. 66 {1918), Vo. J,, pp. S64-S7S, fips. 

 9). — Following up preliminary work previously reported (E. S. R., 82, p. 42*2), 

 the author has obtained results which support the conclusion of Cannon and 

 Free (E. S. R., 37, p. 213) to the effect that soil aeration is a factor no 1 

 important than are water and temperature in plant growth. 



In these experiments carbon dioxid was introduced BUbterraneously Into 

 soil in Wagner pots, the tests employing Capsicum armmum aoort viatum, f.m- 

 tuca tativn. Raphanu* sativus, and Phaseohu vulgaris. 



It Is stated that plants respond differently to carbon dioxid gas added t.> 

 the soil in which they are grown, Christmas pepper, head lettuce, radishes, and 

 string beans all being affected by the addition of carbon dioxid gas to the 

 soil. The effects on root development are greater than those on the aerial 

 portions. Plants were not affected to the same extent by intermittent and 

 constant applications, although a constant treatment of CW cc. of carbon 

 dioxid gas per hour appeared to be sufficient to prevent normal root develop- 

 ment 



Physical factors of transpiration in plants and transpiration in parasitized 

 leaves, .7. Dufrenoy (Rev. 04*. ffOt, 29 (1918), Nn. 20, pp. 565. 566).— This is a 

 synthetic review of the findings and views of a number of authors on factors 

 in transpiration. 



