Thiere, Leipzig, 1876. Espinas published his most remarkable
work, Les Societes animales, in 1877, and in that work he pointed
out the importance of animal societies, and their bearing upon
the preservation of species, and entered upon a most valuable
discussion of the origin of societies. In fact, Espinas's book
contains all that has been written since upon mutual aid, and
many good things besides. If I nevertheless make a special
mention of Kessler's address, it is because he raised mutual aid
to the height of a law much more important in evolution than the
law of mutual struggle. The same ideas were developed next year
(in April 1881) by J. Lanessan in a lecture published in 1882
under this title: La lutte pour l'existence et l'association pour
la lutte. G. Romanes's capital work, Animal Intelligence, was
issued in 1882, and followed next year by the Mental Evolution in
Animals. About the same time (1883), Buchner published another
work, Liebe und Liebes-Leben in der Thierwelt, a second edition
of which was issued in 1885. The idea, as seen, was in the air.

4. Memoirs (Trudy) of the St. Petersburg Society of Naturalists,
vol. xi. 1880.

5. George J. Romanes's Animal Intelligence, 1st ed. p. 233.

6. Pierre Huber's Les fourmis indigees, Geneve, 1861; Forel's
Recherches sur les fourmis de la Suisse, Zurich, 1874, and J.T.
Moggridge's Harvesting Ants and Trapdoor Spiders, London, 1873
and 1874, ought to be in the hands of every boy and girl. See
also: Blanchard's Metamorphoses des Insectes, Paris, 1868; J.H.
Fabre's Souvenirs entomologiques, Paris, 1886; Ebrard's Etudes
des moeurs des fourmis, Geneve, 1864; Sir John Lubbock's Ants,