Dombrowski: Bacteria from Paleozoic Salt Deposits 455 



destruction by mechanical pressure. After considering the depth of our find- 

 ings, we can estimate a maximum of 1400 m. With the normal geothermic 

 gradient, which gives the temperature at a certain level, we get a maximal 

 value of +42° C, which the germs were exposed to during their long latent 

 life. This temperature in no way prevents the preservation of life. 



The cjuestion of which geological specimen is to be examined is of foremost 

 importance. At first I used all sorts of Zechstein salts, while trying out the 

 bacteriological working procedure. But later, I carefully selected the speci- 

 mens to be investigated. All specimens, which came from questionable 

 regions, such as near faults or the upper salt level, were discarded. Specimens 

 showing signs of recrystallization were also discarded. We used only pieces 

 which definitely showed signs of being primary Zechstein salts, and of these only 

 those which came from perfectly undisturbed points in the middle of larger suc- 

 cessions of rock salt, the layers of which were formed normal-hypidiomorphic 

 to allot riomorphic. Their grain size lies in the order of millimeters. But even 

 with this careful selection of specimens, only about every second culture showed 

 results. 



Because it is very probable that the organisms are of primary genesis, we can 

 undertake an estimation of the age of these isolated living bacteria. Because 

 pollen grains were isolated, which served as characteristic fossils, it was rela- 

 tively easy to establish the age of the bacteria. 



We also centered our attention on another aspect of the problem: in undis- 

 turbed geological layers the rock salt has practically no pores, if we disregard 

 the lye enclosures. If the salt is taken out from its natural environment, it 

 will not be subject to the pressure of the overlaying strata anymore. It relaxes 

 and thus increases in volume by a few per cent. Due to this loosening, pores 

 begin to form and air can automatically enter the salt. This would make 

 possible the entering of bacterial contamination from the outside. To prove 

 that this was not happening, we prepared petrographic thin sections of the salt. 

 In examining these, we found the bacteria to be embedded in the crystalline 

 structure of the salt and not in the capillary crevices (figure 1). 



Contrary to the previously shown Paleozoic microorganisms, this form (fig- 

 ure 2) is a direct decendent of the Paleozoic germ, which was obtained by cul- 

 tivation, and identified as Bacillus circulaus. I found this form in three differ- 

 ent Zechstein formations. It is a very rare specimen, which has been described 

 only eight times since 1890. A comparison of the Paleozoic and the Recent 

 representatives of this group is of special interest. When the Recent germs are 

 compared from an evolutionary point of view they are neither older nor younger 

 than the Paleozoic ones, but the Recent type has gone through completely 

 different stages of development. They were not preserved in a latent stage of 

 life, but have probably gone through an immensely great number of cell divi- 

 sions. If it were not for the phenomenon of circular migration, which is pecu- 

 liar to both the Paleozoic and the Recent type, it would be very difficult to find 

 a relationship between the two. 



Comparing them biochemically, we find very distinct differences. Our 3 

 Paleozoic strains show almost identical biochemical properties. The strain 

 found by Kienholz lost all its saccharolytic characteristics, which its Paleozoic 

 relatives had. The only new characteristic is their ability to liquefy gelatine. 



