FERMENTED MILK

diminished also. Under such conditions the rate of absorption is actually more rapid. Yandell and Malcolm C. Henderson suggest that this may explain why pneumonia commonly assumes a fulminating character in elevated localities. These observations are interesting and important. Probably they are in the main correct; but they do not supply a full explanation of all that occurs during the absorption of occluded gases. It is doubtful whether the process can be fully explained on purely physical and chemical grounds. A point to which Yandell and Malcolm C. Henderson do not appear to pay adequate attention, is the carriage of oxygen in the blood as oxy-hremoglobin and of carbon dioxide as sodium bicarbonate. The law concerning pressures of gases does not apply to gases in chemical combination, despite the fact that, if they are in loose combination, they may be given off under the influence of a lowered external pressure. There are several features (not mentioned here) of their thesis that Yandell and Malcolm C. Henderson do not discuss sufficiently fully (perhaps they take their readers' knowledge for granted); but probably all these can be satisfactorily explained by the laws of physiology, physics and chemistry. The thoughtful reader should wish to know why a negative pressure becomes established in the pleural cavity and, if the atmospheric pressure really maintains the pressure of gases in an occluded space at 760 millimetres of mercury, why this negative pressure is aIlowsd to exist in a normal pleural cavity.