One of the most fundamental necessities for the progress of thoracic surgery is a better understanding of the physiology involved. Of the physiologic problems, there is none more important than an accurate knowledge of just what happens when an opening is made in the chest. The effects of open pneumothorax, therefore, should be studied and discussed until as much knowledge as possible has been obtained on this subject. My reason for presenting the matter again is chiefly to encourage a more accurate study of the problem and to dispense with much of the conjecture which exists in the literature.
In 1918, in association with R. D. Bell,1 I reported the results of experiments both on human cadavers and on animals which seemed to change the existing conceptions of the effects of an open pneumothorax. The most important finding in our experiments was that in a normal thorax, one in