rift to the north. The line of tracks in the snow along which the birds
had gone the day before was now cut off short at the edge of the open
water, showing that they had gone, and under the ice-cliffs there was an
appreciable diminution in the number of Emperors left, hardly more than
half remaining of all that we had seen there six days before."[19]

Two days later the emigration was still in full swing, but only the
unemployed seemed to have gone as yet. Those who were nursing chicks were
still huddled under the ice-cliffs, sheltered as much as possible from
the storm. Three days later (October 28) no ice was to be seen in the
Ross Sea: the little bay of ice was gradually being eaten away: the same
exodus was in progress and only a remnant of penguins was still left.

Of the conditions under which the Emperor lays her eggs, the darkness and
cold and blighting winds, of the excessive mothering instinct implanted
in the heart of every bird, male and female, of the mortality and gallant
struggles against almost inconceivable odds, and the final survival of
some 26 per cent of the eggs, I hope to tell in the account of our Winter
Journey, the object of which was to throw light upon the development of
the embryo of this remarkable bird, and through it upon the history of
their ancestors. As Wilson wrote:

"The possibility that we have in the Emperor penguin the nearest approach
to a primitive form not only of a penguin but of a bird makes the future
working out of its embryology a matter of the greatest possible
importance. It was a great disappointment to us that although we
discovered their breeding-ground, and although we were able to bring home
a number of deserted eggs and chicks, we were not able to procure a
series of early embryos by which alone the points of particular interest
can be worked out. To have done this in a proper manner from the spot at
which the Discovery wintered in McMurdo Sound would have involved us in
endless difficulties, for it would have entailed the risks of sledge
travelling in mid-winter with an almost total absence of light. It would
at any time require that a party of three at least, with full camp
equipment, should traverse about a hundred miles of the Barrier surface
in the dark and should, by moonlight, cross over with rope and axe the
immense pressure ridges which form a chaos of crevasses at Cape Crozier.
These ridges, moreover, which have taken a party as much as two hours of
car