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CN RESPIRATION.

But, before we proceed further, I must informyou that the chemical theory of respiration, withwhich you have just been made acquainted, simpleand beautiful as it is, has appeared to many philo-sophers insufficient to explain all the phenomena ofrespiration. Amongst the various modificationsproposed, with a view to improve this theory, thatsuggested by La Grange, Ilnsseufratz, and someother eminent chemists, appears to be the most im-portant. These philosophers suppose that theoxygen, which disappears in respiration, is ab-sorbed by the blood, and carried with it into thecirculation, during which it gradually combineswith the hydrogen and carbone that are successivelyadded to the circulation, forming the water andcarbonic acid which are expelled from the lungsat each expiration. Thus the process, instead ofbeing completed in the lungs, as the former theorysupposes, only begins in that organ, and continuesthroughout the whole circulation.

According to this theory, the florid colour of ar-terial blood depends upon the addition of oxygen,so that this colour gradually vanishes as the bloodpasses from the arterial to the venous state, that isto say, as the oxygen enters into combination withthe hydrogen and carbone during circulation.

CAROLINE.

There does not appear to me to be any verv cs-