GROWTH, FERTILITY, ETC. IN ANIMALS DURING ATTEMPTED ACCLIMATIZATION TO CARBON MONOXIDE

¹ The National Institute for Medical Research, Hampstead

1. Some mice and rabbits maintain their rate of growth when slowly acclimatized to about 0·3 per cent. of carbon monoxide in the inspired air. It is pointed out that man's ability to acclimatize gradually to the gas has never been properly tested, and, although not so resistant as certain animals appear to be, he probably possesses much greater resistance, to such gradual exposure, than has so far been suspected.

2. The heart of the mouse is often much hypertrophied during slow acclimatization, and this organ is regarded as playing a chief part in the powers to acclimatize.

3. The mouse appears to be more easily acclimatized to carbon monoxide than to low oxygen pressure in the air.

4. Mice after acclimatization to 0·30 per cent. carbon monoxide are not fertile; true acclimatization is thus not attained.

5. If carbon monoxide is consumed by living animals when breathing 0·30 per cent. of the gas, the consumption must be of a very low order, as is to be expected from Fenn and Cobb's results for frog's skeletal muscle exposed in vitro to 80 per cent. of the gas.

6. The carbon monoxide pressure in the tissues is less than half that in the inspired air. Oxygen pressures in the tissues are reduced to half the normal value in an acclimatized animal breathing 0·30 per cent. carbon monoxide.

I am indebted to my assistant Mr C. Pergande for much help with this research.