322 



GASOMETRIC-VOLUMETRIC METHODS 



be consulted for the determination of each of these errors. For the 

 two instruments described by them, the algebraic sum of those errors 

 which are constant and independent of the presence of the organism 

 in the respirometer equalled —1.6 X 10-* fA./hr. for the type A, and 



Fig. 97. Glass stopper with 



respirometer tubes attached. 



Fnrm Tobias (1943) 



Fig. 98. Complete Tobias-Gerard 



respirometer assembly. 



From Tobias (191,3) 



—4.2 X lO"'* ij\./\\v. for the type B instrument. The summation of 

 the errors which are dependent on the presence of the organism 

 amounted to 0.147 v for the type A, and 0.407 v for the type B in- 

 strument, where v is the observed value for the volume of oxygen 

 measured. 



(c) Tobias-Gerard Respirometer 



Tobias and Gerard (1941) employed the principle, used earlier 

 by Gerard and Hartline (1934), of placing a small capillary reac- 



