382 



GASOMETRIC-MANOMETRIC METHODS 



The slight initial bend of the respiration curve for diver 17 has nothing to 

 do with the respiration, it simply means that in case of this diver, which was 

 the last one to be placed in the thermostat, the measurements were begun be- 

 fore the initial equalization of i)rossure and temperature had ended. 



Fig. 133. Respiration of amoebae: p = pressure. 

 From Holier (1943) 



(6) 0.1 Microliter or Capillary Diver Technique 



Zeuthen (1943) developed a new type of Cartesian diver for 

 respiration studies which has a gas volume about 100 times smaller 

 than the /xl. diver. These smaller divers, with a gas volume in the 

 range 0.04-0.11 /xl., were designated by Zeuthen as 0.1 (A. or capillary 

 divers. Their smaller volume leads to a refinement of the measure- 

 ment to the point where respiration intensities of 2 X 10"'* to 

 2 X 10"^ lA. oxygen per hour can be determined. In comparative 

 studies with several divers Zeuthen observed an error of measure- 

 ment of 2 X 10"^ lA. oxygen per hour, while variations in the respira- 

 tion of the individual cell during an experiment were much less. 

 Although the greatest respiration rate thus far measured in capil- 

 lary divers is 2 X 10"^ /xl. oxygen per hour, Zeuthen is of the 

 opinion that all rates less than 10"^ /xl. oxygen per hour should be 

 measured in capillary divers of suitable dimensions, while higher 

 rates should be followed in /xl. divers. Aside from the design of the 

 diver pipettes, and the flotation vessel, the apparatus is the same 

 as that used with the /xl. diver. 



(1) THE CAPILLARY DIVER 



Dimensions. The diver (Fig. 134) which is chosen as an 

 example has a gas vol. of 0.072 /xl. It is closed with seals of flotation 

 medium (Mi and Afo). The medium is that of Holter having a 



