sparrows congregated in groups round the bush, keeping up a
constant chattering and noise" (Paper read before the New Zealand
Institute; Nature, Oct. 10, 1891).

21. Brehm, iv. 671 seq.

22. R. Lendenfeld, in Der zoologische Garten, 1889.






CHAPTER II

MUTUAL AID AMONG ANIMALS (continued)

Migrations of birds. Breeding associations. Autumn
societies. Mammals: small number of unsociable species.
Hunting associations of wolves, lions, etc. Societies of
rodents; of ruminants; of monkeys. Mutual Aid in the struggle
for life. Darwin's arguments to prove the struggle for life
within the species. Natural checks to over-multiplication.
Supposed extermination of intermediate links. Elimination of
competition in Nature.