And in the same way it has been supposed that the whales, huge as they are, cannot possibly contain sufficient air for the needs of the creatures during the prolonged period—often nearly an hour—during which they remain under water, since they have no other means of aerating the blood whatever. So it has been assumed that in some mysterious way the vital principle of the air, oxygen, is in some way secreted during the period that the whale is on the surface, a supposition which is somewhat supported by the fact that the whale upon coming to the surface must make so many respirations, always the same in number, before he can seek the depths again, which would point to some process going on in addition to ordinary breathing. Also it would certainly be impossible for him to sink if he inflate
