MECHANISM OF DEATH 



391 



medium over a large number of glass-stoppered bottles 

 which were filled completely so as to leave no air space. 

 The bacteria multiplied readily until the dissolved oxygen 

 in the stoppered bottles was used up. This was deter- 

 mined by chemical analysis. The growth is shown in 

 Table 130 for Ps. fluorescens, and in Table 46, p. 187 

 for Bad. coli. In both cases, growth continues for about 

 one hour after the oxygen supply is exhausted, and then 

 the bacteria begin to die. The death rates were found to 

 decrease decidedly. 



Death of Bad. coli by suffocation is very slow as compared with 

 that of Ps. fluorescens, the death-rate being only about one-tenth. 

 The data suggest a logarithmic order of death, with considerable 

 variability of resistance of the individual cells. There is an indica- 



Table 131. — Successive Death Rates op Suffocating Cells 



Ps. fluor- 

 escens. 

 I 



II. 



0.146 

 0.021 

 0.095 

 0.050 



0.173 

 0.016 

 0.145 

 0.047 



0.124 



0.160 

 0.039 



0.122 



0.135 

 0.021 



0.095 



0.095 

 0.023 



0.048 



0.131 

 0.020 



0.039 

 0.100 



0.029 

 0.078 



Bad. coli. 

 I 



II 



0.0156 

 0.0015 

 0.0050 



0.0110 

 0.0019 

 0.0121 



0.0132 



0.0075 



0.0032 



0.0033 



0.0011 



0.0018 



0.0003 



0.0013 



0.0005 



0.0012 



tion of a short initial increase in the death rate; this may be just the 

 period of changing over from no death to the final death rate. The 

 continuation of multiplication for about one hour after the oxygen 

 is completely used up suggests storage of oxygen, either physically 

 or chemically, and deserves attention. 



Possibly, the absence of oxygen produces a compound in the cell 

 which hinders further cell activity. These experiments offer no 

 opportunity to decide whether this is the case. The fundamental 

 reaction of death by suffocation is still unknown. 



