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CH. II.] expels particles rendered effete, and these are supplied by others from without, during inspiration; and this continues so long as life endures." It emanates from an early stage of physiology, no doubt, but yet it does clearly intimate that without such an alternation life could not be maintained—that a renewing power from without, and an expulsion of something prejudicial from within, are necessary to animal existence. Democritus (of Abdera), Anaxagoras and Diogenes are cited by  as believing respiration to be necessary for all  (in opposition to himself, who limited the process to air-breathing animals), and he has given their account of the process in fishes and oysters (molluscs). " Anaxagoras says that fishes, during respiration, discharge the water through the branchiæ, and that then, as there may not be a vacuum, they draw in air which is in the mouth; and Diogenes maintains that, when fishes discharge the water through the branchiæ, they draw in, by means of the void created in the mouth, the air which is ever present in water and encircling the mouth." Democritus advanced a step nearer to modern teaching, in accounting for fishes dying when out of the water by their then taking in too much air; as, when in the water, they can take in only a moderate quantity." But all this was objected to,, by Aristotle, both because of his own more restricted views of respiration, and of the apparent discrepance of the theories with common sense, and thus was he led, in