[170] Cæsium occurs in various plants and the possibility of poisoning by this element must be considered. It is hoped that the writer may be able to undertake a more thorough pharmacological study of this element. [171] Acqua, C. Sull'accumulo di Sostanze Radioattive nei Vegetali. Atti della Reale Accad. dei Lincei, 5 s, vol. 16, sem. 2, p. 357. 1907. [172] Compare Meltzer, S. J. Toxicity of Magnesium Nitrate When Given by Mouth. Science, vol. 26, p. 473. 1907. [173] Burgassi, G. Modificaz. del Ricambio per Azione dello Stronzio. Archiv. di Farmacol., vol. 6, p. 551. 1907. [174] Noyes, A. A., and Bray, W. C. System of Qualitative Analysis for the Common Elements. Journ. Amer. Chem. Soc., vol. 29, pp. 168, 172, and 191. 1907. NOTE.--Barium sulphate is nontoxic on account of its insolubility. Orfila fed 16-24 grams to dogs without causing any disturbance. Bary, A. Beitr. z. Baryumwirkung. Dorpat, 1888, p. 25. [175] Sprengel, C. Von den Substanzen der Ackerbrume und des Untergrundes, Journ. f. Techn. u. OEkon. Chem., vol. 3, p. 313. 1828. [176] Eckard, G. E. Baryt, ein Bestandtheil der Asche des Buchenholzes. Annal. der Chem. u. Pharm., n. s., vol. 23, p. 294. 1856. [177] Forchhammer, J. G. Ueber den Einfluss des Kochsalzes auf die Bildung der Mineralien. Annal. d. Physik u. Chemie, vol. 5, p. 91. 1905.--Lutterkorth, H. Kohlensäurer Baryt, ein Bestandtheil des Sandsteines in der Gegend von Göttingen. Annal. d. Chem. u. Pharm., n. s., vol. 23, p. 296. 1856. [178] Dworzak, H. Baryt unter den Aschenbestandtheilen des. Ægyptischen Weizen. Landw. Versuchs.-Stat., vol. 17, p. 398. 1874. [179] Knop, W. Analysen von Nilabsatz. Landw. Versuchs.-Stat., vol. 17, p. 65. 1874.--Compare also Demoussy, E., Absorption par les Plantes de Quelques Sels Solubles, Thése, Paris, 1899.--Knop, W., Einige neue Resultate der Untersuchung über die Ernährung der Pflanze, Ber. ü. Verhandl. d. königl. sächs. Gesells. d. Wissens. zu Leipzig, Math. Phys. Cl., vol. 29, p. 113, 1877.--Suzuki, U., Can Strontium and Barium Replace Calcium in Phænogams? Bul. Coll. Agric. Tokio Imp. Univ., vol. 4, p. 69, 1900-1902. [180] Hornberger, R. Ueber d. Vorkommen d. Baryums in d. Pflanze und im Boden. Landw. Versuchs.-Stat., vol. 51, p. 473. 1899. [181] Roscoe, H. E., and Schorlemmer, C. Treatise on Chemistry, vol. 2, p. 455. 1897. [182] Hillebrand, W. F. Analysis of Silicate and Carbonate Rocks. Dept. Interior, U. S. Geol. Survey, Bul. 305, p. 18. 1907. [183] This report came from the Plant Analysis Laboratory of the Bureau of Chemistry, a different one from that which later controlled the writer's tests quantitatively and qualitatively. In other words, the conclusions of the writer as to the presence of barium were controlled by three separate individuals.