| Abstrakt: |
In a paper presented before the Radiological Society of North America, in December, 1922, I outlined some studies we were making concerning the normal chest. It was our conception that the pulmonary structures undergo certain changes from birth to old age as a result of environment and the normal fibrosis that takes place in body tissue from age, and that these changes, when viewed as a whole, must be considered as one great normal process. Since these changes are progressive, accumulative and never ending, we gave them the name "the progression of the chest." That is, there is a fibrous change which takes place in all tissue as a result of age, and which must be considered normal. Likewise, there are certain changes or deposits which take place in the lung tissue as a result of infection or dust irritation, and, if the lung masters this infection or irritation, it |
