Pulmonary atelectasis occurs in two forms, microscopic and macroscopic. The microscopic form has attracted almost no attention so far. It is described in three reports on autopsies in cases of asthma and undoubtedly deserves much more careful study.1

The macroscopic form was described early in the nineteenth century. Laennec,2 discussing a typical case from the practice of Andral,3 considered it a purely nervous form of asthma. The case is similar in symptomatology and gross pathology to the cases now being recognized as massive collapse.

At about the same time, English surgeons were studying the condition in children as congenital failure of the lung to expand. Following its experimental reproduction by plugging a bronchus in 1845,4 the condition was forgotten clinically until the works of Pasteur5 in 1910 to 1914 called attention to its occurrence after operation. This excellent work failed to receive any attention in America until the observations of