be considered, not only as an argument in favour of a pre-human origin of moral instincts, but also as a law of Nature and a factor of evolution.  Espinas devoted his main attention to such animal societies (ants, bees) as are established upon a physiological division of labour, and though his work is full of admirable hints in all possible directions, it was written at a time when the evolution of human societies could not yet be treated with the knowledge we now possess.  Lanessan’s lecture has more the character of a brilliantly laid-out general plan of a work, in which mutual support would be dealt with, beginning with rocks in the sea, and then passing in review the world of plants, of animals and men.  As to Buchner’s work, suggestive though it is and rich in facts, I could not agree with its leading idea.  The book begins with a hymn to Love, and nearly all its illustrations are intended to prove the existence of love and sympathy among animals.  However, to reduce animal sociability to love and sympathy means to reduce its generality and its importance, just as human ethics based upon love and personal sympathy only have contributed to narrow the comprehension of the moral feeling as a whole.  It is not love to my neighbour—­whom I often do not know at all—­which induces me to seize a pail of water and to rush towards his house when I see it on fire; it is a far wider, even though more vague feeling or instinct of human solidarity and sociability which moves me.  So it is also with animals.  It is not love, and not even sympathy (understood in its proper sense) which induces a herd of ruminants or of horses to form a ring in order to resist an attack of wolves; not love which induces wolves to form a pack for hunting; not love which induces kittens or lambs to play, or a dozen of species of young birds to spend their days together in the autumn; and it is neither love nor personal sympathy which induces many thousand fallow-deer scattered over a territory as large as France to form into a score of separate herds, all marching towards a given spot, in order to cross there a river.  It is a feeling infinitely wider than love or personal sympathy—­an instinct that has been slowly developed among animals and men in the course of an extremely long evolution, and which has taught animals and men alike the force they can borrow from the practice of mutual aid and support, and the joys they can find in social life.

The importance of this distinction will be easily appreciated by the student of animal psychology, and the more so by the student of human ethics.  Love, sympathy and self-sacrifice certainly play an immense part in the progressive development of our moral feelings.  But it is not love and not even sympathy upon which Society is based in mankind.  It is the conscience—­be it only at the stage of an instinct—­of human solidarity.  It is the unconscious recognition of the force that is borrowed by each man from the practice of mutual aid; of the close dependency of