HEAT AND ELECTRIC ENERGY 49 



common "hay bacillus" grows at 6° C.^ Rising temperatures 

 increase the velocity of the biochemical reactions of proto- 

 plasm up to an optimum temperature, beyond which they are in- 

 creasingly injurious and finally fatal to all organisms. In hot 

 springs some of the Cyanophyceaj (blue-green algae), primitive 

 plants intermediate in evolution between bacteria and algae, 

 sustain temperatures as high as 63° C. and, as a rule, are killed 

 by a temperature of 73° C, which is probably the coagulation 

 point of their proteins. Setchell found bacteria living in water 

 of hot springs at 89° C.- In the next higher order of the Chlo- 

 rophyceas (green algae) the temperature fatal to life is lower, 

 being 43° C.^ Very much higher temperatures are endured by 

 the spores of certain bacilli which survive until temperatures 

 of from 105° C. to 120° C. are reached. There appears to be 

 no known limit to the amount of dry cold which they can 

 withstand.^ 



It is this power of the relatively water-free spores to resist 

 heat and cold which has suggested to Richter (1865), to Kel- 

 vin, and to Arrhenius (1908) that living germs may have per- 

 vaded space and may have reached our planet either in com- 

 pany with meteorites (Kelvin)'^ or driven by the pressure of 

 light (Arrhenius).^ The fact that so far as we know Hfe on the 

 earth has only originated once or during one period, and not 

 repeatedly, does not appear to favor these hypotheses; nor is 

 it courageous to put off the problem of life origin into cosmic 



^Jordan, Edwin 0., 1908, pp. 67, 68. "Op. ciL, p. 68. 



^ Loeb, Jacques, 1906, p. 106. 



^ Cultures of bacteria have even been exposed to the temperature of liquid hydrogen 

 (about — 250° C.) without destroying their vitality or sensibly impairing their biologic 

 qualities. This temperature is far below that at which any chemical reaction is known 

 to take place, and is only about 23 degrees above the absolute zero point at which, it is 

 believed, molecular movement ceases. On the other hand, when bacteria are frozen in 

 water during the formation of natural ice the death rate is high. See Jordan, Edwin O., 

 1908, p. 69. 



* Poulton, Edward B., 1896, p. 818. 



* Pirsson, Louis V., and Schuchert, Charles, 1915, pp. 535, 536. 



