260 THE POWER OF RESISTANCE TO EXTREMES 



satisfactorily determined l , for large quantities of poisons can be passively 

 secreted in an insoluble form in the cell-sap, and such poisons as prussic 

 acid are only formed after the death of the cell. Digitaline, and such 

 alkaloids as morphine, atropine, eserine, muscarine, and veratrine, seem to 

 exert little or no poisonous action on most plants, whereas strychnine seems 

 often to act as a strong poison 2 . The resistance to copper salts varies 

 greatly in different plants, for Spirogyra and other algae die in water 

 containing i part of copper in 1,000,000,000 parts of water 3 , whereas 

 Penicillium glaucnm is still able to grow in solutions containing I 

 gramme-molecule in 0-75 litre (21 per cent.) 4 . This solution retards 

 growth more than would be expected from its concentration, but the 

 poisonous action is very slight, and the conidia may remain living for 

 a long time in a saturated solution containing, at 20 C., 25-5 per cent, of 

 copper sulphate. Other fungi are less resistant, for Pulst has shown that 

 Aspergillus niger, Botrytis cinerea, and Mucor mucedo grow little or not at 

 all in solutions containing 0-016 per cent, of copper sulphate (i gramme- 

 molecule in i ,000 litres). The spores (or germ-tubes) of Ustilagineae 5 

 are still more sensitive, and are killed by the superficial impregnation 

 of infected corn with copper sulphate. Other fungi again are not more 

 resistant than are flowering plants, and although small percentages of 

 copper salts kill most bacteria, the spores of Bacillus anthracis are highly 

 resistant 6 . 



1 Schiibler, Flora, 1827, p. 757; Cornevin, Compt. rend., 1891,. T. cxm, p. 274; H. de 

 Varigny, Rev. gen. d. Bot., 1892, T. iv, p. 407. 



3 Bokorny, Pfliiger's Archiv, 1896, Bd. LXIV, p. 299; Schwarz, Wirkungen von Alkaloiden 

 aufPflanzen, Erlanger Dissertation, 1897; Overton, Vierteljahrsschrift der Naturf. Ges. in Zurich, 

 1896, Bd. XLI, p. 401; 1899, Bd. XLIV, p. 108 ; Clark, Botanical Gazette, 1899, Vol. xxviir, 

 p. 394; Fliigge, Mikroorganismen, 1896, 3. Aufl., Bd. I, p. 472 ; Sigmund, Versuchsstat, 1896, 

 Bd. XT.VII, p. i ; Ewart, Protoplasmic Streaming, Clar. Press, 1903, p. Si. 



3 Hence water distilled from a copper vessel is usually poisonous to Spirogyra and similar algae. 

 Cf. also Copeland and Kahlenberg, Trans, of the Wisconsin Acad. of Sciences, 1899, Vol. xir, 

 p. 454. Pure distilled water is not poisonous. See Loew and Schulze, Landw. Jahrb., 1891, 

 Bd. XX, p. 235; Deherain and Demoussy, Compt. rend., 1901, T. CXXXII, p. 532. It may, 

 however, injure organisms which require a certain osmotic concentration in the surrounding 

 medium. Ficker (Lebensdauer und Absterben von pathogenen Keimen, 1898, p. 71) finds that 

 this is the case with certain bacteria. 



4 That sulphate of copper is not especially poisonous to Penicillium glaucum has long been 

 known. Cf. Jager, Flora, 1843, p. 486; Chatin, ibid., 1845, p. 214; Preuss, Bot. Ztg., 1848, 

 p. 409; de Seynes, Bull. d. 1. Soc. Bot. d. France, 1895, pp. 451, 482. Pulst (quoted by Pfeffer) 

 has recently obtained the above values. Apparently some varieties are less resistant and may cease 

 to grow in i to 3 per cent, solutions. Cf. Clark, 1. c., p. 393. Copper nitrate acts like copper 

 sulphate. 



5 Wuthrich, Zeitschr. f. Pflnnzenkrankheiten, 1892, Bd. II, p. 93; Tschirch, Das Kupfer, 1893, 

 p. 44; Clark, I.e.; Stevens, ibid., 1898, Vol. xxvi, p. 385 (fungi); Kahlenberg and True, 

 ibid., 1896, Vol. xxn, p. 96; Heald, ibid., p. 139 (Phanerogams); Coupin, Compt. rend., 

 1900, T. cxxvn, p. 400; Frank, Arbeiten a. d. Biol. Abth. f. Land- u. Forstwirthschaft, 1900, 

 I, Heft 2, p. 127; Devaux, Compt. rend., 1901, T. cxxxn, p. 717. 



6 Krbnig and Paul, Zeitschr. f. Hygiene u. Infectionskrankheiten, 1897, Bd. XXV, p. 63. See 

 also Tschirch, 1. c., p. 46. 



