650 CONDITIONS AFFECTING THE DEATH OF FUNGI. 



&c., whenever the amount of water has fallen below 60 

 to 70 per cent. ; more accurate determination of these 

 limits is, however, wanting. 



Light, Among other influences light and pressure seem scarcely 



electricity, to esert any noticeable effect on the development of the 

 and pressure. , . ^ T^I-P * . i 



lower fungi. Certes and Locnin round that yeast could break 



up sugar under a pressure of 300 to 400 atmospheres ; in like 

 manner putrefactive phenomena occurred in fluids which 

 were kept under a pressure of 350 to 500 atmospheres. 

 Electricity, in the form of the constant galvanic current, 

 causes cessation of the multiplication of the bacteria ; this 

 effect is due to the electrolytic action of the current, which 

 leads to the production at the positive pole of a distinctly 

 acid reaction, and at the negative pole of a distinctly alkaline 

 one. No influence is noticeable when the current is weak ; 

 the effect is not produced till at least two powerful elements 

 are employed. 



Temperature. Of much greater practical importance is the tempera- 

 ture of the nutrient medium. At a low temperature as 

 well as at a high temperature multiplication of bacteria 

 (and also of mould fungi) ceases; but in almost all species 

 the limit of the low and high temperature appears to be 

 different. In the case of many organisms these limits 

 have not yet been accurately determined. In the case of 

 many saprophytes (the water bacteria, the organisms 

 formerly grouped under the term ''bacterium termo," 

 &c.) slight growth may occur at a temperature of + 6 

 C., and development only ceases at a temperature of 

 from 4 to 5 C. On the other hand, the lowest limit of 

 growth for the spirillum of Asiatic cholera is from 15 to 

 16 C.; for the bacilli of glanders, about 22 C.; and 

 for the tubercle bacilli, 33 C. Cessation of multipli- 

 cation as the result of higher temperatures occurs : in 

 the case of the lactic acid bacillus, above 45*3 C.; in the 

 case of bacterium termo, from 40 to 43 C.; in the case 

 of bacillus subtilis, at 50 to 55 C. The higher limit 

 is difficult to ascertain, because the temperature which 

 only leads to temporary cessation of vital activity, and 

 that which more especially when it acts for a consider- 

 able time causes permanent loss of certain properties, 

 usually lie very close to each other. 



