264 THE POWER OF RESISTANCE TO EXTREMES 



Goppert 1 , the newer in part by Frank 2 . The further literature is given in the 

 previous pages. 



Zopf 3 gives a summary of the works on fungi, and most of the literature on 

 bacteria is given by Fliigge 4 . As regards disinfection it must be remembered 

 that a stoppage of growth is more readily produced than is complete death. Thus 

 Koch 5 has shown that the growth of the anthrax bacillus is retarded by car- 

 bolic acid in a concentration of i : 1,250, and stopped when the concentration 

 reaches i : 850, whereas death is only produced in 0-25 to 0-5 per cent, solutions, 

 and the spores may even remain living a few days in 5 per cent, carbolic acid 

 solutions. 



SECTION 73. The Detailed Action of Poisons. 



Every poisonous action involves an interaction between a chemical 

 substance and the protoplasm. When sufficiently attenuated a poison may 

 induce reactions which are either innocuous or even of use to the protoplast. 

 This stimulatory action of poisons is of equal importance to their fatally 

 injurious effect when sufficiently concentrated. Many food-materials act 

 as poisons when concentrated, and the same may indeed apply to most 

 substances which when dilute act as exciting or directive stimuli. 



Poisons may produce an acceleration as well as a retardation of 

 single functions or of the general activity. Thus small doses of the most 

 varied poisons increase growth, respiration, and the production of heat G . 



Similarly chloroform and other chemical agencies may awaken or 

 accelerate growth, and under special circumstances may quicken the 

 movements of organs or protoplasmic streaming 7 . In increased concen- 

 tration a poisonous effect is exercised in all cases, and no preliminary 

 excitation may be shown when sensitive plants are used, even when the 

 poison is applied in attenuated form. Sugar, for instance, retards the 

 growth of nitrate and nitrite bacteria even when a very small amount of 

 it is present. 



Particular poisons may affect various functions to different degrees, 

 and some may inhibit growth, movement, or photosynthesis without 

 causing a cessation of respiration and metabolism. Whether these latter 

 may even be accelerated under such circumstances is not certain, but is 



1 Goppert, De acidi hydrocyanic! vi in plantas commentatio, 1827. 

 3 Frank, Krankheiten d. Pflanzen, 2. Aufl., 1894, Bd. i, p. 310. 



3 Pilze, 1890, p. 219. 



4 Mikroorganismen, 1896, 2. Aufl., Bd. i, p. 446. 



5 Fliigge, 1. c., p. 466. 



6 On the acceleration of respiration by poisons see the recent works by Jacobi, Flora, 1899, 

 p. 289 ; Morkowine, Rev. gen. d. Bot., 1899, T. xi, p. 289. 



7 [Best shown by treating slowly streaming or nearly quiescent cells with dilute ether, alcohol, or 

 glycerine.] 



