I have a further case to record of a different experiment in co-operative parenthood, in this case necessitated through the severities of the struggle of life. In the same antarctic regions where the Adélie penguins make their home there dwells another penguin, the great emperor penguin. This bird has a sad history; never, during the whole course of its life, does it touch dry land; the vast ice-fields form its only home, and it has to brave the perils of the open water in its search for food. Under such circumstances the struggle for life is severe, and the parent-birds have the greatest difficulty to rear the young. In these ice-nurseries, incubation in the usual manner in a nest is impossible; a new and curious method is adopted. Each mother lays but a single egg, which is placed for warmth and safety in a “brood-spot” situated at the back of the feet, where it is covered by the overlapping feathers of the abdomen. Even this care is not rewarded always, and many of the eggs perish. Owing to the difficult incubation, a large percentage of brooding birds are left without eggs and young. And the curious thing is that this loss seems to increase the desire for offspring, until the parental instinct becomes a tormenting passion. This is what happens. Each childless bird strives to adopt a child from the more fortunate parents; and this leads to a competition in parenthood, which of its kind is without parallel. Not only the duty of incubation, but afterwards caring for the young chicks, is carried out not by one bird only, but by a dozen or more, which stand patiently round for a chance to seize either a chicken or an egg. Nor is it, as might be expected, the mothers alone who are seized by the passion of thwarted maternity; the fathers help their childless wives in their efforts to steal offspring. Every bird, male as well as female, has developed the “brood-spot,” and has the same bare patch of skin at the lower part of the abdomen against which the egg, when possessed, is pressed for warmth.