"Henry Robertson Bowers (left), Dr Wilson (centre), and Apsley George Benet Cherry-Gerrard (right) with loaded sled, ready to leave for Cape Crozier, 27 June 1911. Photograph taken by Herbert George Ponting, during the British Antarctic ('Terra Nova') Expedition (1910-1913)." 
Wilson, Bowers, and Cherry left on an expedition to Cape Crozier to collect penguin eggs.
This was Wilson's pet project, to study the embryology of Emperor penguin eggs, available unhatched only in the middle of winter. "It is because the Emperor is probably the most primitive bird in existence," Cherry explained later, "that the working out of his embryology is so important. The embryo shows remains of the development of an animal in former ages and former states; it recapitulates its former lives. The embryo of an Emperor may prove the missing link between birds and the reptiles from which birds have sprung."  The only known rookery was at Cape Crozier, and Wilson reckoned that the eggs would be laid in the beginning of July.
They took two 9-foot sledges lashed together, with 790 lbs. of gear and supplies for six weeks, travelling in the almost-complete darkness of midwinter. It would be the "worst journey in the world" after which Cherry later named his book.
 Alexander Turnbull Library, National Library of New Zealand.
 Apsley Cherry-Garrard, The Worst Journey in the World, ch.VII. Wilson had been deeply influenced by the work of the German biologist and philosopher Ernst Haeckel, who proposed that the embryonic stages of an animal repeat the evolutionary history of its type. It is thought today that flightless birds evolved from those with flight, rather than the other way around.