446 THE ZOOLOGIST. 
organized flesh and blood, and appreciate the indubitable fact 
that, if it ceased, the whole equilibrium of life would be imme- 
diately upset, we are justified in viewing migration as being, 
after the fact of life itself, the grandest phenomenon of biology. 
The present condition of the Antarctic Regions, and the 
comparatively small area of land within the southern temperate 
zone, act in disturbing the balance of the annual flow of birds. 
The data are not available for any safe conclusions on the marine 
alge of the southern oceans, and on the migrations of fish and 
piscivorous birds; but if seems only reasonable to expect that 
beyond the Equator fishes play a large part in maintaining the 
equilibrium of life. Towards the north, bird migration oscillates 
across a line that is considerably nearer the Pole than the 
Equator, and a great number of species never reach the Tropical 
Zone, even in winter. 
The fact seems to be well established that those birds which 
reach the most northerly parts in summer migrate farthest south 
in winter. Asarule, they are remarkable for an apparatus of 
flight far beyond the ordinarily observed needs of life; and it is 
very curious that so little attention has been paid to this matter. 
A Grey Plover, for example, is so powerful a flier that I cannot 
imagine one being taken by a bird of prey except by chance; 
and there are many circumstances, unnecessary to mention 
here, suggesting that the powerful wings of wading birds are not 
primarily intended for purposes of defence. Certainly they seem 
out of all proportion to the feeding requirements of the birds, 
and we can only look upon them as being essentially the 
organs of migration, and, in a way, merely secondary as organs 
of flight—a paradoxical statement that is yet worth serious 
attention. Viewed in this way, such long wings enable the bird 
to overcome the barrier of distance protecting the Arctic animals, 
and are thus analogous to the beak of the Curlew or the eyes of 
the Owls as specialized feeding organs. 
Most wading birds are great migrants, or, rather, it should 
be put the other way about in saying that many migrants are 
wading birds. In a general sense a wader is a bird specialized 
for an existence in non-arboreal marshes. We know that the 
land around the North Pole, and many other parts of the higher 
latitudes of the Palearctic Region, are, in summer, typical 
