292 GENERAL PHYSIOLOGY 



temperatures of more than 100 C. without losing their capacity 

 of life. 



For the present an explanation of these puzzling facts is want- 

 ing. It can only be assumed that the proteids in these organisms 

 occur in a condition in which they cannot be made to coagulate 

 by high temperatures, even, as in the case of the spores of the 

 hay-bacillus, by a boiling temperature. The two assumptions, 

 that, in spite of the temperature of the surrounding medium, the 

 living substance is not heated to the coagulation-point of the 

 proteid, and that the vital capacity is maintained in spite of the 

 coagulation of the proteids in them, are equally improbable. It 

 is not yet known upon what molecular changes the process of 

 coagulation is based, and by what conditions apart from the 

 known factors its appearance is influenced. When more is known 

 upon these questions, some light will be thrown also upon the 

 puzzling phenomena mentioned above. 



5. Pressure 



Like temperature, the pressure surrounding bodies has an 

 influence upon their chemical constitution. This is especially 

 noticeable in cases where the chemical body exists in a medium 

 with the constituents of which it is in chemical relation. If this 

 condition is fulfilled, if a chemical body exists in a gaseous or 

 liquid medium containing substances that have a chemical affinity 

 for it, then, by an increase of the pressure, a chemical combination 

 between the body and the substances in the medium can take 

 place, and by a subsequent decrease of the pressure a decomposition 

 into the previous constituents can occur. This phenomenon depends 

 upon an antagonism between the vibrations of the atoms and the 

 pressure. With a greater pressure the atoms become crowded 

 together, hence more atoms of the medium are able to come into 

 contact with atoms of the body ; with a less pressure the 

 vibrations become again so great that the atoms are disengaged 

 from the loose combination. 



Living substance exists in such a condition. It lives in a 

 medium, either air or water, with which it can undergo chemical 

 exchange. It is clear, therefore, that the pressure, either of the 

 air or of the water, will have a great significance for life, and that 

 a pressure within definite limits must belong to the general vital 

 conditions. 



Unfortunately this condition has been very little investigated 

 thus far, and at present it is possible to state only in part under 

 what pressure of air or water life in general is still possible, and 

 between what limits of pressure it is confined in its present form 

 upon the earth's surface. The experimental investigation of this 



