Sand-wasp, memory of locality in, [62];
- author's experiments with, [63].
Sarcoptes Hominis, death-feigning in, [209].
Satin bird, æstheticism in the male, [128];
- author's observations of, [128].
Sea-urchin, eyes of, [16].
Snail, eyes of, [19];
- visual powers of, [19];
- courtship of, [20];
- location of sense of direction in, [194];
- author's experiments with, [194];
- author's experiments in demonstrating homing sense in the, [194].
Snake, love of young in, [140];
- author's experiment in testing parental affection of, [140];
- sense of direction and "homing instinct" in, [198];
- author's observations of "homing instinct" in, [198].
Sole, the origin of unilateral eyes in the, [9].
Song-sparrow, memory of individuals in, [77];
- parental affection in, [143].
Spaniel, a laughing, [89].
Spider, memory in, [72];
- recognition of individuals by, [73];
- love of music in the, [108];
- author's experiments with piano on, [108];
- author's experiments with pipe organ on, [109];
- Reclain's observations on the love of music in, [109];
- decorative instinct present in, [110];
- peculiar web spun by, [110];
- parental affection in, [135];
- author's experiment in testing parental love of, [135];
- use of implement (pebble anchor) by, [222].
Squirrel, memory in the, [70].
Stentor polymorphus, nervous system of, [46];
- observations of and experiments with, [47];
- conscious determination in, [47];
- ganglia of, [47].
Strongalognathus, degeneration caused by the habit of slave-making in, [155], [156], [157].

Tabanus atratus, balancers of, [33];
- loss of equilibrium in, [33];
- anatomy of balancers of, [34];
- auditory hairs of, [34].
Termes, kinds of individuals in a colony of, [161];
- number of eggs laid by queen of, [162];
- size of gravid queen, [162];
- New Mexican, [163];
- soldiers and workers of, [163];
- instincts and reasoning powers of, [164].
Terrier, love of music in, [113];
- musical discrimination in, [113];
- abstract ideation in, [216].
Tinctumutation, definition of, [182];
- location of color-changing sense centre in, [183].
Toad, memory in the, [87];
- a performing, [87];
- parental affection in the Surinam, [140].
Triticum repens, sick dogs medicate themselves with, [220].
Turkey, memory of individuals in the, [76];
- recognition of property rights by the, [221].

Vanessa, tinctumutation in the larva of, [192].
Viper, death-feigning in the, [207].
Volition, definition of conscious, [39];
- physiological aspect of, [40].

Wasp, memory in the, [62];
- author's experiments in testing memory in the, [63], [69];
- memory of kindred in the, [65], [69];
- memory of locality and of events in the, [85];
- knowledge derived from a single experience by a, [85];
- length of life in the mud-dauber, [138];
- evidence of reason in the mud-dauber, [149], [150];
- psychic actualities of easy acquirement in the ant, the bee, and the, [151];
- faculty of computing in the mason, [169];
- author's experiments in testing the computing faculty in the, [170];
- method of preparing food for the male and female grubs used by the mason, [170].
Water-louse, sense of direction in the, [194].
Wren, distress and grief evinced by, [93];
- recognition of individuals by, [93];
- gratitude shown by, [94].

ECONOMICS.

BY
EDWARD THOMAS DEVINE, Ph.D.,
General Secretary of The Charity Organization Society of the City of
New York; Sometime Fellow in the University of Pennsylvania;
and Staff Lecturer of the American Society
for the Extension of University Teaching.