66 



DE. BASTIAN ON THE 



turbid*. Acting in this way I found that fluids heated to 131° F. 

 (55° C.) for ten minutes would ferment, but tliat when heated to 

 140° F. (60° C.) for the same period they remained quite clear and 

 pure. I inferred therefore that the temperature of 131° F. was not 

 sufficient to kill, but that one of 110° F. was adequate to destroy 

 the organisms and germs introduced into the nojirishing liquid. 

 I also ascertained that when the exposure to heat was prolonged 

 to four hours such organisms were killed at still lower tempera- 

 turesf. 



In the following year Prof. Cohn and Dr. Horwath made almost 

 similar experiments in regard to the death -point of Bacteria, but 

 not for TorulaB. It does not appear that they were then aware of 

 my investigations. They, however, arrived at results almost pre- 

 cisely similar, as may be seen when Prof. Cohn X sa,} s : — 

 " These experiments demonstrated without exception that no 

 Bacteria were developed in the flasks which were kept at a tem- 

 perature of from 60°-62° C. for an liour, and that the contained 

 fluid remained clear; on the other hand, flasks contaiuins: Bacteria 

 fluid which had only been heated to 50° C. or 40° C. became 

 clouded, in consequence of the multiplication of Bacteria, in a time 

 varying from two to three days." 



" One need scarcely mention," he adds, " that in flasks heated to 

 70°, 80°, 90° C. there was never any cloudiness. The fact that the 

 cloudiness in a flask which has only been subjected to a tempera- 

 ture of 50°-52° C. for one hour show^s itself much sooner than in one 

 which has been kept at the same temperature for two hours, leads 

 one to suppose that 60° C. is apparently not the lowest tempera- 

 ture at which Bacteria are killed, but that perhaps a lower degree 

 of heat would be sufficient to prevent their multiplication." 



In the year 1873 I returned to this subject in order to ascer- 

 tain whether Bacteria and Vibriones would be killed at the same 

 temperatures in organic infusions as they had been found to be in 

 a neutral saline solution. A large number of experiments were 



* The noiirisbing liquid employed was much simpler than that of Pasteur 

 or of Cohn, since it consisted merely of a 2 per cent, solution in distilled water 

 of the neutral ammonium tartrate with about ^ per cent, of a neutral sodic 

 phosphate. I had ascertained even in 1870 (' Nature,' July 14, p. 222) that 

 both Bacteria and Torulse would grow and multiply in a simple solution of 

 ammonium tartrate, and therefore had recognized before Prof. Cohn that these 

 organisms could take their carbon from such a compound as tartaric acid. 



t 'Modes of Origin of Lowest Organisms,' 1871, p. fi9. 



\ Beitrage zur Biologie der Pflanzen, l^' Bd., 2*" Heft, 1872, p. 219. 



