BACTERIA AND ICE 167 



the recent researches of Dr. Krause, by typhoid, 

 anthrax, tubercle, and some other bacteria of pre- 

 serving unimpaired not only their vitality but their 

 virulence after having undergone for a period of 

 twenty hours a pressure of no less than that of 

 500 atmospheres. When we reflect that a pressure 

 of 500 atmospheres is equal to a pressure of about 

 7,500 pounds to the square inch, and that the 

 normal pressure under which life is maintained 

 upon this planet is approximately that of fifteen 

 pounds to the square inch, this bacterial victory 

 over physical conditions will be more readily ap- 

 preciated. 



The more intimate becomes our knowledge of 

 bacteria, the more must we marvel at the equip- 

 ment with which they have been provided for 

 enabling them to maintain themselves in the 

 struggle for existence a struggle which is as 

 severe and as remorseless in this lowly region as it 

 is in those domains the inhabitants of which have 

 risen to far loftier heights on the great ladder of 

 life. 



