president’s address. 
283 
time emit a beautiful perfume. If the colours of flowers have 
been developed by the selection exercised by insects, this is doubtless 
also the case with the odours. 
Insects which visit plants and thus distribute pollen, belong 
mostly to the families Hymenoptera, Lepidoptera, and Diptera : but 
many flowers are visited by insects for shelter only, especially those 
which are bell-shaped, or those which are fluffy. Fertilization is 
sometimes caused by the movements of the larvae, and not by the 
perfect insects. Thus Blowflies deposit their eggs in the carrion 
flowers, and the Maggots in searching for food press the pollen 
masses downward to the stigma. 
The importance of the parts played respectively by the senses of 
sight and smell, in luring insects to melliferous flowers, has been 
much in dispute. Some naturalists insist that sight has the greater 
influence. Lord Avebury has recorded experiments which he made 
to obtain evidence of the power of Bees to distinguish colours, lie 
placed slips of glass with honey on papers of various colours, and 
when they had made a few visits he found that if the papers were 
transposed the Bees followed the colours. 
An incident narrated by a well-known naturalist bears on this 
question, lie was walking in Newgate Street when his attention 
was caught by a White Butterfly, and as lie was surprised to see 
the insect in such a locality, he watched it carefully, and observed 
that it was flying round a lady’s hat which was trimmed with many 
artificial flowers, and it hovered for some time over this scentless 
bouquet. 
On the other hand, Professor Plateau of Ghent, after the labour 
of most careful observations, the results of which he has communi- 
cated to the SocietS Enlomologigue de Belgique regards the sense 
of smell as the chief agent in guiding insects to the flowers, and 
he doubts whether their supposed choice of colours really exists. 
Professor Plateau removed the coloured corollas from widely different 
flowers, and found that they were visited by Bees and Butterflies 
just as freely as those which had not been so treated, and he 
writes in answer to a letter from myself, “ It is thus very natural to 
suppose that insects are attracted to the flowers by another sense 
