We have previously intimated that the œdema present in the early stages of the reaction is to be looked upon as an inflammatory œdema or better as a true serous exudate, and must not be confused with the transudation of fluids in non-inflammatory conditions. We have on several occasions collected the fluid expressed from the soggy lungs and have made some determinations of their chemical qualities. The difficulty immediately arises in separating the materials arising from cellular degeneration from the natural constituents of the serous exudate. We were unable to obtain specimens in which laked blood was not present, so that even though the cellular constituents and fibrin were removed, decomposition products could not be separated. The analyses, however, gave a differentiation from the transudate seen in renal and cardiac conditions. During the period of the accumulation of this inflammatory fluid the clinician could often recognize a profuse watery exudate within the lung or even observed an abundant serous discharge arising in bronchi and trachea. At times the quantity of expectoration was great. Frothy serous fluid accumulated in the air passages and would periodically be expectorated. At other times the hemorrhage was of quite serious extent and the patient would suddenly bring up several mouthfuls or more of bright blood. This pulmonary hemorrhage was without manifestations different from the acute illness with cyanosis of other individuals. The two most acute cases, which we have referred to above, were of this kind, both of them having marked hæmoptysis with the loss of upwards of a pint of blood at a time.