“…Since Pitt (1900) first reported a torn emphysematous bulla attached to a fibrous adhesion, other authors (Hopkins, 1937;Hartzell, 1942) have either produced evidence of or have directly observed (Hansen, 1949) haemorrhage from a torn bulla. Yet others (Davidson and Simpson, 1940;Arst, Lahey, and Kunkel, 1950;Irwin, 1951) have shown that vessels in torn adhesions can be the source of haemorrhage or have witnessed this at thoracotomy (Beatty and Frelick, 1952;Myers et al, 1951;Ross, Dugan, and Farber, 1953), where the appearances closely resemble the occasional haemorrhagic complication in the operation of thoracotomy with division of pleural adhesions (Sellors, 1951).…”