in LIVING MATTER 71 



contractile protoplasm of Amoebae coagulated sometimes at 40 C., 

 sometimes at 45 C. For plant cells, Max Schultze found that the 

 fatal temperature could be raised to 47 C. Other elementary 

 organisms, indeed, support much higher temperatures, which would 

 seem incredible if they were not substantiated by direct measure- 

 ment. In the hot baths of Casamicciola, e.g., certain Algae flourish 

 at a temperature of 63 C., while, according to Ehrenberg, some 

 of the ciliated Infusoria (Occillaria or Rotifera) can live* at a 

 temperature of 81 - 85 C.' More surprising still, the spores 

 of Anthrax, according to Koch, Brefeld and others, can support a 

 temperature of over 100 C.,and only lose their vitality completely 

 after three hours' dry heat at 140 C. It must be remembered in 

 explanation that the protoplasm of these organisms consists of 

 proteins combined in such a way that they do not coagulate nor 

 decompose at these high temperatures. 



The minimum temperature compatible with life is equally 

 surprising. While as a rule the poikilothermic animals and plants 

 die when the temperature falls to such a point that the water 

 imbibed by the protoplasm freezes, Raoul Pictet's latest experi- 

 ments show that a temperature of less than C. is not necessarily 

 fatal to certain organisms. In fact he ascertained positively that 

 fishes frozen at a temperature of - 15 C. can recover their vitality, 

 provided the thawing is effected with great caution. If, however, 

 the fall in temperature amounts to - 20 C., they inevitably perish. 

 Frogs, on the contrary, tolerate a temperature of - 28 C., centipedes 

 one of - 50 C., while, lastly, bacteria can survive exposure to 

 - 100 C. 



Here we reach the vexed question whether frozen animals, 

 capable of recovering their vitality on thawing, are in a state of 

 minimal or of absolute latent vitality. Although the latter 

 possibility is not excluded, Pictet's experiments do not seem to 

 favour this hypothesis. If these frozen fishes were in a condition 

 of latent vitality, it is difficult to see why they should not be 

 indifferent to a fall of temperature below - 15 C., which they can 

 survive. It seems more rational to admit that at this temperature 

 metabolic exchanges are still maintained, although reduced to the 

 lowest terms, and that death ensues when metabolism ceases 

 altogether. 



V. The pressure of the air and water in which these organisms 

 live must also be considered among the general conditions of life. 

 It is indeed evident a priori that pressure must act against the 

 thermal vibrations of the atoms ; when therefore there is a marked 

 rise of pressure obstructing the thermal vibrations, this favours 

 the appearance of chemical combinations, while a marked diminu- 

 tion, by increasing the amplitude of the said vibrations, must 

 weaken the mutual attraction of the atoms and dissociate the 

 unstable chemical combinations. 



