454 Annals New York Academy of Sciences 



For the duration of this work we set up cuhure plates on which germs in the 

 air coukl germinate, which in most cases did not happen. If the germs of 

 the air did germinate, however, they were brought into saHne solutions to 

 prove their tolerance to salt. This test always showed an intolerance to salt, 

 so that there was no identity to the bacteria that came from the salt specimens. 



In counter-checks we sterilized salt crystals for 4 hours at 200° C., before 

 investigating them bacteriologically in the prementioned manner. These 

 crystals proved to be sterile. We also examined crystals coming up from a 

 depth of more than 4300 m.; in the Mesozoic era these salts lay about 1000 

 meters deeper than today. At this depth the temperature is at least 160° C, 

 and as expected these salt specimens also showed no sign of life. 



Now, how can we find an explanation for the conservation of life over such 

 an extended period of time, that is for over 180 million years? There are two 

 possibilities. First, one is reminded of the method for conserving bacteria that 

 is practiced today, i.e., dehydration at low temperatures. If one extracts al- 

 most all the water from the protein of micro-organisms, it is possible to preserve 

 them for years without changing any of their particular characteristics, although 

 there is no metabolic activity whatsoever. We know of certain germs, which 

 lived for more than 30 years, although their metabolism was totally inhibited. 

 Starke and Harrington (1931) consider the vitality of dried bacteria as un- 

 limited. If this is correct, then the hypothesis of finding living organisms in 

 Paleozoic layers could not have received better support, and we would then 

 have found a way of understanding the survival of these organisms over such 

 long periods of time. Second, there is the possibility of reversibly denaturing 

 protein by salification. This method can also be used on higher organisms with 

 good results. For instance, the protein from the eggs of sea urchins can be de- 

 naturized in a saturated solution of ammonium sulfate. After months, this 

 process is reversible by simply removing the salts. The eggs retain the ability 

 to be fertilized. Perhaps in our specific case both methods, that of dehydration 

 and that of salification, were in effect. 



If this interpretation was true, then the method should be reproducible in a 

 laboratory experiment. For this experimental reproduction we used Pseu- 

 domonas halocrenaea, which were isolated from Zechstein salts. This bacterium 

 does not bear spores. 



If the nutrient solution in which it started growing is slowly dehydrated, 

 the bacterium will die. This will not happen if one slowly saturates the 

 solution by adding 1 gm. of salt per week. This substratum is now slowly de- 

 hydrated, until all salts are completely dry and crystalline. In this dry state 

 it can be kept for long periods of time. When bringing these salts into a fresh 

 nutrient solution again, the original vitality of the bacterium can be re-estab- 

 lished. 



I would like to point out a further peculiarity: the optimal temperature for 

 many of the germs that we found lies between +45 and +vS5° C, which is 

 astonishingly high. But, elucidating enough, this temperature corresponds 

 exactly to that temperature which, geologists say, was present when the Zech- 

 stein sea was slowly drying up. 



I believe that this correspondence of temperatures is certainly not accidental. 

 Because the bacteria were embedded in the crystals, they were assured against 



