A large proportion of all deaths, perhaps the majority from all ultimate causes, are immediately due to failure of respiration. The prevention of even a small fraction of them will amount in the aggregate to the saving of a very large number of lives. The procedures and apparatus of which I shall speak have already demonstrated their capacity to save these lives, and probably more. The methods lie in a nearly new field of therapeutics, a field which we may call inhalational therapy. It is sometimes a useful accessory and sequel to artificial respiration. But it is of much greater scope than mere artificial respiration.