192 
REPORTS OF SOCIETIES. 
Aug., 1890. 
degeneration was given in the relative weight of brain and body in the 
wild and domestic duck; in the latter case the brain having been 
reduced to half its weight in relation to the body weight. It had been 
well said that two thousand years’ association with man had reduced 
the bird to a state of idiotcy. The lecturer showed that there is a 
good deal of indirect evidence of the existence of the aesthetic sense— 
for instance, as a rule, males are more beautiful than females in the 
animal kingdom ; in some cases, however, where the females take an 
active part in courtship, and the males are coy and exercise selection, 
the females are the more ornamentally coloured. This is the case 
with the common white butterflies in England, the Meadow Brown, 
the Grayliug, and some of the Hairstreaks. Another class of indirect 
evidence was drawn from insects. Where the females can be shown to 
have degenerated (and probably lost the ®stketic sense), the beauty of 
the male disappears. Instances of this, in a descending scale of 
degeneration, are to be found in the Emperor Moth, the Vapourer, and 
the Psychid®. Examination of the pup® shows that the females of 
the first once possessed highly developed antenn® ; of the second, 
fully developed wings: of the third, the ordinary appendages of a 
perfect insect. These have been lost in course of time, and a corre¬ 
sponding loss of brightness of colour has taken place in the males— 
the Emperor being little changed, the Vapourer retaining only 
the one white spot of a once varied pattern, the Psychid® having 
grown uniformly dingy. Some direct evidence from insects was then 
adduced, based on the observation by two American naturalists of the 
extraordinary attitudes assumed in courtship by the males of a genus 
of spiders (Attid®). These varied from the ostentatious display of 
some highly coloured portion of the body to the evolutions of an 
intricate dance. The females manifested a very decided opinion 
indeed as to the artistic merits of these courtship dances, and the 
fate of the unsuccessful postulant was generally to be eaten on the spot. 
(Some lantern slides were afterwards shown illustrating some of the 
most remarkable of these attitudes). Since Darwin’s time the evi¬ 
dence of the presence of the ®sthetic sense in two well-known cases 
has been considerably strengthened—one is the discovery of the 
part played by its highly decorated wing spots in the courtship of the 
Argus pheasant, large prepared circuses having been found in the 
Malayan Islands, with special perch occupied by critical female, and 
separate entrance, from which the males successively defile to display 
their attractions before her. The other is the discovery of a new 
Bower Bird in New Guinea, with artistic proclivities developed far 
beyond those of its Australian relative. This bird constructs conical 
huts of a species of Epiphyte, producing leaves and flowers long after 
its building into the hut, faces this with a carefully laid mossy lawn, 
to be in its turn decorated with bright shells, flowers, and fruits, 
regularly removed and replaced as they fade. All this simply for use 
as a kind of assembly room, having nothing to do with the economy 
of nesting, which is conducted in trees. Final facts adduced as telling 
against Wallace’s theory of intensity of colour being due to super¬ 
abundant vigour and vitality were—The existence of bright colour only 
in species which areabroad when colourcaube seen—not in night-flying 
birds and insects ; the absence of bright colour on the wings of such 
species as vibrate them so rapidly that the colours would be indistin¬ 
guishable, e. g ., humming birds; and the presence of these colours on 
the wings of slow-flying species; the presence of colour disposed in 
such lines and bands as to be seen to most advantage by the female 
when the male is approaching her, i. e., from the head backwards. 
