VIEWS ON MIGRATION. 17 



any proportionate numbers. Is it possible that the 



most northerly birds hibernate and pass the long 



Arctic winter in torpidity as so many other boreal 



creatures are known to do ? I express an opinion 



neither one way nor the other, but allude to the 



facts as suggesting an interesting field of inquiry. It 



has also been remarked repeatedly that abnormally 



early individuals of Corn Crakes and Swallows have 



been noticed in or near districts where unusually 



late ones were observed during the previous 



autumn. 



The above may be taken as the pith of the 



evidence in favour of hibernation ; it is now only 



fair that the evidence against it should be briefly 



discussed. I think we may at once dismiss 



subaqueous hibernation as applied to birds as a 



physical impossibility. The species on which this 



portion of the theory is based could not live for 



even a few moments under the surface ; water is 



not their element; whilst the sudden arrest of 



vital activity and the abrupt transition from 



mercurial energy to torpor is absolutely fatal to 



the supposition that they should seek such a 



retreat. We have, however, the Duke of Argyll's 



interesting experiences of birds suddenly assuming 



a comatose condition, which may bear directly on 



hibernation under other conditions. The theory of 



subaqueous hibernation probably had its origin in 



the fact that Swallows are particularly fond of 



frequenting large sheets of water, especially in 



autumn, at which season vast numbers often resort 



c 



