390 DISCOVERY REPORTS 



rise to the top of the stored fluid and accompany the next sample of blood into the upper 

 part for analysis. 



Experiments of the kind performed with sample no. loo may be extended by checking 

 the final nitrogen content of the blood as soon as the absorption of the nitrogen is com- 

 plete. This is done by driving out the remaining air nitrogen, sealing the upper stopcock 

 with mercury, and immediately evacuating the blood. Nitrogen in the reagents is of 

 course deducted from the volume obtained. If this part of the experiment is done the 

 instant the absorption is complete, the same volume of nitrogen can be extracted from 

 the blood as is theoretically contained in it, namely the original content plus nitrogen 

 gone into solution. But if this extraction is delayed nitrogen disappears and the final 

 content is less than the original plus added gas. The nitrogen capacity experiment on 

 sample loo (p. 387) was completed by extraction of the gases from the blood at 50 min. 

 after the beginning of the experiment. The nitrogen content was 2-47 vol. per cent, 

 whereas the volume of nitrogen dissolved in the blood plus its original content was 

 2-62 vol. per cent. The volume of nitrogen which had disappeared was therefore 

 0-15 vol. per cent uncorrected, or 0-13 vol. per cent at n.t.p. 



A number of experiments on these lines were performed both with adult and foetal 

 whale blood, difl^erent times being allowed after complete solution of nitrogen before the 

 final blood gases were estimated. The volumes of blood and air employed were varied 

 at random, so that there was no possibility of the disappearance of nitrogen being the 

 result of a constant error. The experiments were all performed at room temperature 

 since it was not practicable to reproduce the temperature conditions of the living whale 

 in these experiments on board ship. Similar results have been obtained by aerating 

 blood and immediately covering it with a thick layer of paraffin. Successive samples are 

 pipetted from beneath the oil and analysed as before. 



This disappearance of nitrogen goes far towards explaining the low nitrogen contents 

 of the fresh samples of blood (Table III). It is impossible that the blood could have been 

 exposed to nitrogen at less than atmospheric pressure during the last minutes of a 

 whale's life; the probabilities are, on the evidence of urine and allantoic fluid, that the 

 air pressure in the lungs was considerably above normal. The slight supersaturation 

 which has been observed in the urine indicates, in conjunction with the resuhs of these 

 experiments, that the blood was momentarily supersaturated and had not become de- 

 nitrogenated before it reached the kidneys through which some of the excess nitrogen 

 diffused into the urine. At atmospheric pressure, as we have seen, the blood can take 

 more than 2 vol. per cent into solution, and yet such a nitrogen content is seldom found. 

 It seems very likely that the sequence of events which formed the basis of the experi- 

 ments described above is in fact a recapitulation of what happens to the blood when it 

 passes through the lungs, becomes aerated, and subsequently in its passage through the 

 arteries and veins becomes denitrogenated by some internal mechanism. The samples, 

 which were drawn from arteries in the heads of dead whales, had stood long enough for 

 more or less denitrogenation to have occurred according to the time which had elapsed 

 since death and other factors. 



