THE EFFECTS OF DECOMPRESSION 247 



the pressure could be lowered from 8 atm. to 1 atm. in about 10 

 to 60 seconds. It was also provided with a pin-point opening 

 through which the period of decompression could be made to 

 occupy one, two, or more hours. 



A cat, two rabbits, two rats, and two mice were placed in this 

 chamber and the pressure raised to 8 atm. A ventilation current 

 was maintained. All the animals appeared to be perfectly normal. 

 At the end of an hour rapid decompression was brought about. 

 The chamber filled with mist owing to the cooling of the expanded 

 air. When the mist cleared we saw that the cat and one rabbit 

 were dead, while the other rabbit was in violent tetanic convulsions. 



On opening the chamber the rats were found to be dead. 



The second rabbit died also and the mice alone survived. 



There was emphysema of all the tissues and frothing of the 

 blood in the right heart and lung. In the albino rats we could 

 see extensive retinal haemorrhages. 



A large cat, a rabbit, two white rats and two mice were com- 

 pressed to 8 atm. in 50 minutes, and kept at this pressure for 

 1 hour. Decompression occupied 1 hour. None of the animals 

 showed any discomfort. 



A Rhesus monkey, a rat, and two mice were compressed to 

 8 atm. for 4 hours. The animals seemed untroubled by the pres- 

 sure. Decompression was started at 4.30 P.M. by opening the 

 small tap ; the last part of the decompression was hastened, and 

 when at 5.25 the pressure registered 10 Ibs. to the sq. inch, the 

 large valve was opened and the pressure quickly brought to 

 zero. On opening the chamber the monkey and the other animals 

 seemed perfectly normal. On removing the monkey from the 

 chamber it struggled to escape, but in the course of a minute or 

 two suddenly became quiet and lay on its side gasping, and 

 with a peculiar cry. It gradually got more and more dyspnoeic, 

 and its lips, tongue, and face became markedly cyanotic. Despite 

 energetic artificial respiration it died in about 10 minutes after 

 removal from the chamber. 



On opening the right heart a little deep purple frothy blood 

 exuded. Small air columns were to be seen in several of the 

 mesenteric veins. 



The other animals in this experiment did not show any de- 

 compression symptoms. The cause of the trouble was the ac- 

 celeration of the last part of the decompression. 



