RESPIRATORY METABOLISM 369 



organism for purposes of storage, the R.Q. may reach a value of 1.4. 

 If fat or protein is being converted to carbohydrate, there will be a cor- 

 responding tendency for the R.Q. to be lowered. A high value for the 

 R.Q. can also arise whenever CO, is removed from a compound with- 

 out the consumption of O^, or whenever an oxygen debt accumulates 

 (during heavy exercise). Whenever an oxygen debt is being removed, 

 the R.Q. may fall to extremely low values (during rest after exercise). 

 Unusual values of R.Q. may be obtained if substrates other than carbo- 

 hydrates, fats, or proteins are being consumed. In the case of very rapid 

 protozoan growth on substrates of organic acids, the R.Q. should vary 

 with the oxygen content of the molecule being oxidized (acetic acid, 

 1.0; proprionic acid, 0.85; butyric acid, 0.80). 



The respiratory quotient of an organism may be calculated with almost 

 any of the manometric methods described above, if separate measure- 

 ments are made with and without a COa-absorbing alkali in the respira- 

 tory chamber. In this case, one set of readings (with KOH) will give a 

 measure of the O2 consumed, and the other set (without KOH) will 

 be an Index of the difference between CO2 given off and O2 consumed. 

 From this the R.Q. may be calculated, provided no NHg is evolved and 

 no CO2 is retained in the immersion fluid. If these complications arise, 

 suitable modifications may be introduced. The use of somewhat more 

 complicated manometer chambers allows measurements of simultaneous 

 O2 consumption and CO2 production to be made on the same material 

 (Dixon, 1934). For the Protozoa this method seems preferable because, 

 in addition to its usual advantages, it prevents the results from being 

 affected by the possible secretion of ammonia (Specht, 1935) and 

 other bases (e.g., sodium carbonate from oxidation of Na-acetate, Jahn, 

 1935a). However, even this method does not correct for the possible 

 evolution of hydrogen or methane (cf. Trichomonas foetus, Andrews 

 and von Brand, 1938). 



For the ciliates, several measurements of R.Q. have been made. Wa- 

 chendorff (1912) reported R.Q. values of about 0.3 for Colpidium, but 

 in view of later developments it seems as if this material should be re- 

 examined with more modern methods. Emerson (1929) studied the 

 respiration of Blepharisma undulans and found an R.Q. slightly less 

 than 1.0. Daniel (1931) obtained an R.Q. of 0.84 for Balantidium colt, 

 but the possible effects of bacteria were not well controlled. Amberson 



