MIGRA TION 569 



tralians, while among those races who have little or no need to 

 exercise it, such as people in the highest state of civilization, and of 

 them especially dwellers in towns, the faculty — comparatively weak 

 to begin with and undeveloped by practice — perishes through disuse. 

 If this variability in possessing the sense of direction ^ in the human 

 species be thus admitted, there can be no impropriety in inferring 

 that the lower animals may have the faculty in a degree out of 

 all proportion Avith even those people that have it most. Just as some 

 men surpass others in powers of hearing, sight or smell, and many 

 animals excel all men in these respects, of all animals the sense of 

 direction would naturally attain the greatest perfection in Birds, 

 for they are endowed "s^ith and exercise the greatest power of loco- 

 motion. In urging this opinion there would seem to be no 

 theorizing : it is merely arguing from the known to the unknown. 



Nevertheless it is right to take cognizance of all suggestions 

 that seem to be reasonable, and among them is one put forth by 

 Prof. Mobius {I)as Ausland, No. 33, pp. 648, 649, 14 Aug. 

 1882) to the effect that Birds performing long migrations over sea 

 may be guided by observing the roll of the waves. The possibility 

 of this cannot be denied if the roll be constantly in one direction as 

 seems likely to be in that part of the Pacific Ocean to which his 

 remarks especially refer ; but obviously it will not hold good for 

 the stormy waters of the North Atlantic, where a swell may be set 

 up from any point of the compass, and the American Golden Plovers 

 that yearly resort with such punctuality to "the still-vext Ber- 

 moothes " would assuredly get but little help on their passage 

 thither, or in its continuation to the Antilles, from the set of the 

 billows over which they pass — ever varying Avith the inconstant 

 winds. 



Other authors there are who rely on Avhat they call " instinct " 

 as an explanation of this wonderful faculty. This with them is 

 simply a way of evading the difficulty before us, if it does not 

 indeed remove the question altogether from the domain of scientific 

 enquiry. Rejecting such a mode of treatment, Prof. Palmen meets 

 it in a fairer spirit. He asserts {Fogl. Flyttn. p. 195), that migrants 

 are led by the older and stronger individuals among them, and, 

 observing that most of those which stray from their right course 

 are yearlings that have never before taken the journey, he ascribes 

 the due performance of the flight to " experience." But, granting 



^ I have no wish to urge this sense of direction as a " sixth sense," as has been 

 imputed to me by Dr. "Weismann {Nature, xix. pp. 579, 580, 24 April 1879). 

 What it may be called does not concern me in the least. I know that it exists, and 

 is wholly independent of intellectual forces, as in myself I had proof of the fact 

 in my younger days, but want of exercise has impaired its eflBcacy so as to render 

 it almost obsolete. Some would perhaps attribute the effect to "unconscious 

 cerebration," and I do not object to the phrase if it seems more explanatory. 



