394 DISCOVERY REPORTS 



A portion of this culture was treated in the way which has been described for the 

 experiments to show nitrogen disappearance. 



Nitrogen which disappeared ... ... ... 0-36 vol. per cent 



Time 23 minutes 



Oxygen consumption ... ... ... ... 1-58 vol. per cent 



Ratio of oxygen consumed to nitrogen removed 4-40 



It will be noticed that the initial nitrogen content of the culture was below the expected 

 figure of I vol. per cent. 



A sample of foetal blood, taken 13. i. 33 and kept for 14 days, was examined. The 

 nitrogen content of the sample, which had been standing open to the air, was 0-89 vol. 

 per cent, and the oxygen content o-o8 vol. per cent. On being shaken with air in the 

 burette this culture immediately absorbed 1-53 vol. per cent nitrogen, making the 

 nitrogen capacity up to 2-42 vol. per cent. At the same time 1-57 vol. per cent oxygen 

 were absorbed from the air. Spectroscopic examination of this sample showed that 

 there was no trace of haemoglobin present, which suggests that the oxygen was ap- 

 propriated by the X organisms. After z\ hours the sample had disposed of 0-64 vol. per 

 cent nitrogen, and all the oxygen, 1-57 vol. per cent, which had been taken up was 

 consumed. The ratio of oxygen consumption to nitrogen removal was 2-45. 



Professor Krogh has rightly pointed out that the oxygen consumption recorded in 

 this and other experiments can hardly represent the oxygen requirements of the 

 mechanism of nitrogen removal, since the total oxygen in the blood at full saturation 

 would be insufficient to account for the disappearance of nitrogen taken up at 10 atmo- 

 spheres pressure and there would be nothing left for the whale's metabolism proper. 

 He has also pointed out that asphvxic blood may absorb much oxygen which is not 

 applied to nitrogen fixation and that therefore the observed ratio does not reflect normal 

 conditions. 



Infected pig's blood. Since it was apparent that the ^organisms reproduced rapidly, 

 opportunity was taken to infect fresh pig's blood from a culture. The fresh pig's blood 

 was divided into two portions, and all the usual manipulations were performed with the 

 first. No absorption of nitrogen either temporary or permanent was observed. The 

 second portion, 100 cc, was infected (20. i. 33) with 5 cc. of a three weeks old culture 

 and left overnight at 30° C. The following day the blood was seen to have become de- 

 oxygenated, and on aerating the blood it was apparent that something in it was consuming 

 oxygen. Experiments with nitrogen showed a decrease in nit.''ogen content of 0-02 vol. 

 per cent in 50 min., a volume so small as to be within the limits of error proper to the 

 experiment. 



Another sample (20 cc.) of fresh pig's blood was infected (21. i. 33) with i cc. of a 

 sixteen days old culture of foetal blood. Distinct de-oxygenation of the infected blood 

 was apparent after i hour. This blood disposed of 0-62 vol. per cent nitrogen in 2 hr. 

 10 min. A smear of this blood was seen to contain about 10 million organisms per c.mm. 

 No disappearance of nitrogen occurred in the uninfected control. 



