398 



DISCOVERY REPORTS 



CARBON DIOXIDE IN WHALE BLOOD 

 Carbon dioxide content. A number of estimations of the carbon dioxide content 

 of whale blood were made both at South Georgia and in the factory ship. Since samples 

 of blood were always taken from arterioles in the head, the contents recorded are, of 

 course, those of arterial blood. In view of the high concentrations of carbon dioxide 

 found in various body fluids, it is unlikely that at the end of a long dive, such as usually 

 preceded the death of the whale, there would be much difference in this respect between 

 arterial and venous blood. The following figures were obtained: 



In human blood the carbon dioxide content of whole blood oxygenated is approxi- 

 mately 68 vol. per cent when the partial pressure of carbon dioxide is equal to 100 mm. 

 of mercury (Bock, Field, and Adair, 1924) and 43 vol. per cent when the partial pressure 

 equals 30 mm. of mercury. It therefore appears by comparison with human blood that 

 the partial pressure of carbon dioxide responsible for the contents of carbon dioxide 

 found in whale blood varies for the most part between 30 and 100 mm. of mercury. 

 If partial pressures above 100 mm. of mercury occurred during diving, it is probable 

 that the blood would become saturated in respect of its power of taking carbon dioxide 

 into combination and any further carbon dioxide would be in physical solution and 

 easily transmitted to the other body fluids by diffusion. Some attempt was made to 

 assess the alkali reserve by equilibrating blood with air containing carbon dioxide at 

 40 mm. of mercury. Variable results were obtained, ranging from 30-0 to 50-9 vol. per 

 cent, and it is considered that the acid condition of the blood mentioned above was 

 sufficient to render observations of this kind useless. 



Carbonic anhydrase. Two specimens of frozen blood were submitted to Dr F. J. W. 

 Roughton, for the estimation of the catalyst which accelerates both reactions of the 

 reversible process HaCOg^HgO + CO2, and which has been found in blood corpuscles 

 (Brinkman, Margaria, Meldrum, and Roughton, 1932). Dr Roughton kindly estimated 

 the potency of this enzyme in adult and foetal blood. The following communication has 

 been received from him : 



I define provisionally the unit of enzyme as that amount which, when added to 4 cc. of a mixture 

 of M/5 phosphate buffer (pH 6-8) with M/5 NaHCOj in equal parts, doubles the rate of COj 



