262 THE POWER OF RESISTANCE TO EXTREMES 



well as by poisons dissolved in these media. On the other hand, the 

 action of poisons appears in many cases to be increased in turgid plants by 

 a rise of temperature 1 . Furthermore, the presence of other substances may 

 cause a soluble poison to be precipitated, or converted into an innocuous 

 compound. Solutions of sodium and calcium chloride exert a poisonous 

 action upon pollen-grains which is absent when they are grown in inorganic 

 nutrient solutions or in water 2 . This is possibly the result of mass-action, 

 the displacement of potassium or calcium fatally affecting the constitution 

 of the protoplast 3 . Bacteria and fungi can, however, withstand concen- 

 trated solutions of salt, although large amounts penetrate the protoplasts. 

 The injurious action might also be due to the production of functional 

 disharmony, but it has not been determined to what degree particular 

 substances may so alter the properties and condition of tone of the 

 organism as to render it more or less resistant to poisons 4 . 



As in the case of man and other animals 5 , plants can also be gradually 

 accustomed to doses of poisons which would have previously proved fatal. 

 Certain anaerobic bacteria can in this way accommodate themselves to the 

 presence of oxygen. Sorel 6 has found that the presence of 170 milligrammes 

 of hydrofluoric acid per litre stops the growth of beer-yeast, whereas after 

 gradual accommodation it may continue to grow in solutions containing 

 i gramme of acid per litre. Various authors 7 have shown that bacteria can 

 be accustomed to strong doses of metallic poisons. Trambusti, for instance, 

 found that Friedlander's pneumonia bacillus could be brought to grow in 

 the presence of i part of bichloride of mercury per 2,000 of water, although 

 previously solutions of i in 15,000 proved fatal. Further, bacteria grown 

 in an acid solution are more resistant to acids than when grown in alkaline 

 ones 8 . 



Pulst was able to accustom Penicillium glaucum to large doses of 



1 Cf. Fliigge, Mikroorganismen, 1896, 3. Aufl., p. 450 ; Loew, System d. Giftwirkungen, 1893, 

 p. 8; Heider, Centralbl. f. Bact., 1891, Bd. IX, p. 321 ; Chudiakow, Centralbl. f. Bact., 1898, 

 2. Abth., Bd. IV, p. 391. Schwarz's statement (Wirkung von Alkaloiden auf Pflanzen, 1897, p. 48), 

 that light acts more injuriously in the presence of alkaloids, requires further proof. 



2 Lidforss, Jahrb. f. wiss. Bot., 1896, Bd. xxix, p. 36; 1899, Bd. xxxm, p. 232. Correns 

 (Bot. Ztg. Orig., 1896, p. 26) states that calcium salts act injuriously on Drosera. 



3 Cf. Loeb, American Journal of Physiology, 1900, Vol. Ill, p. 327. 



4 On antagonistic poisons cf. Kunkel, Toxicologie, 1899, p. 36. On atropine and muscarine cf. 

 Ewart, On the Physics and Physiology of Protoplasmic Streaming in Plants, Clar. Press, 1903, 

 pp. 82, 83. The problems of immunity are of similar nature. Cf. Fliigge, 1. c., p. 341. 



5 Robert, Lehrb. der Intoxicationen, 1893, p. 151 ; Loew, 1. c., p. 80; Davenport, Experimental 

 Morphology, 1897, Vol. i, p. 30 (infusoria, &c.). 



6 Sorel, Compt. rend., 1894, T. cxvin, p. 253. 



7 Kossiakoff, Ann. d. 1'Inst. Pasteur, 1887, T. I, p. 465 (boric acid, chloride of mercury) ; 

 Trambusti, Centralbl. f. Bact., 1893, Bd. xm, p. 673. Cf. also Dieudonne, Biol. Centralbl., 

 1895, Bd. xv, p. 109. 



8 Fliigge, 1. c., p. 457. On the accommodation of Flagellatae to strychnine cf. Klebs, Unters. 

 a. d. Bot. Inst. zu Tubingen, 1883, Bd. I, p. 289. 



