EFFECTS OF PRESSURE 



853 



due to a large experimental error associated with the measurements of small 

 inhibitions. However, in all cases, the calculated volume changes vary 

 with the pressure, and in the case of ethanol, change in sign at very high 

 pressures. This may be related to the different effects of pressure on de- 

 naturation in the different pressure ranges, as mentioned above, but could 

 also be due to changes on a more cellular level, for example a liquefaction 

 of the structural units of the luminescent system. 



Completely satisfactory explanations for the effects of pressure on lu- 

 minescence inhibition must await further experimentation on bacterial 



2000 



4000 



6000 psi 



PRESSURE 



Fig. 15-26. Effects of pressure on the ethanol inhibition of lumines- 

 cence in Photobacterium at j^H 7. The figures on tlie curves show 

 the ethanol concentrations. The curves were replotted from the 

 curves of Johnson et al. (1945). 



extracts or otherwise purified systems, with particular attention to the site 

 or sites of inhibitor action and the operation of the system under physio- 

 logical conditions as far as possible, so that approximately the same steady 

 state as occurs intracellularly can be attained. The results obtained on 

 cellular suspensions indicate to the author that the mechanisms are per- 

 haps more complex than has been assumed. It would also be very interesting 

 to find out how the effects of the more usuallv used inhibitors are modified 



