IV. GASOMETRIC TECHNIQUES 



As in the usual macro techniques, both volumetric and manometric 

 methods have been employed for studies on single cells and small 

 cellular aggregates of a well-defined nature. While some are simply 

 refinements of the more macro methods which have been modified 

 for the use of small quantities, other methods involve principles 

 hitherto not applied to gasometric measurements, e.g., Cartesian 

 diver manometry. 



No mention will be made of the Warburg or Barcroft apparatus 

 not only because they are adapted to measurements of a relatively 

 macro order, but also because they have been thoroughly treated in 

 previously published works such as those of Dixon ( 1943) and Um- 

 breite^aL (1945). 



A. VOLUMETRIC 



The gasometric techniques of histo- and cytochemical interest 

 which have been based on volumetry have been developed chiefly for 

 respiration studies. In addition to these, gas analysis techniques 

 devised for use with very small volumes of blood will also be in- 

 cluded, since they may prove useful in some investigations. 



•The advantage of volumetric over manometric apparatus for gaso- 

 metric measurements depends largely on the fact that the former 

 enables direct measurement of gas volume without the necessity of 

 determining the volume of the apparatus. Furthermore, volumetric 

 apparatus permits experimentation at constant pressure, which may 

 be advantageous when a large proportion of liquid is present. How- 

 ever, the determination of the volume of gasometric apparatus is 

 no great problem, and the choice of the technique need not be based 

 on this factor. The particular nature and magnitude of the gas 

 changes to be considered, combined with the availability of the ap- 

 paratus and the personal tastes of the experimenter, will be more 

 cogent factors in the selection of a technique. 



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