PHYSIOLOGY OF THE FLOWER. IIg 
ments are consequently displayed and insects invited to the feast, 
she still shows her economy. Guests might come who were not 
of sufficient importance, and the banquet be wasted on them ; for 
it is only when insects have a certain shape, size, or weight that 
she requires their visits, and can use them profitably for her 
purposes. She requires, moreover, that they should make their 
entrance by the main portal, which she has specially adapted to 
suit their and her requirements. All insignificant and unre- 
munerative visitors, all such, moreover, as would creep in by the 
back entrance, must be kept out... .”? 
We will now first of all consider, in a general way, the most 
important features, and then briefly review the arrangements 
found in certain well-known flowers. 
Conspicuousness.—The corolla, calyx, bracts, and even the 
flower-stalk, may all display more or less colour. In the simpler 
flowers yellows are displayed, which seem attractive to small 
insects and beetles. Whzte in a great many cases either attracts 
small insects or night-flying ones. A walk round a flower-garden 
in the dusk will show how conspicuous white flowers are at this 
time. ed is found in many of the most complex flowers, and 
reddish-brown blooms are often visited by wasps and carrion 
insects. Purple and blue are the rarest colours. They are pre- 
ferred by bees. Aggregation of flowers of course makes them 
much more conspicuous than they would otherwise be, as a 
blossoming gorse-bush or bed of foxgloves will show. This is 
one reason for the existence of inflorescences, and the small size 
or absence of bracts in many of them. Even very small flowers 
may be made striking by aggregation, as is shown in parsnip, 
hemlock, &c., and Composites like sunflower and daisy. Flowers 
may even possess a much enlarged perianth (accompanied by 
corresponding reduction of the essential organs), by which their 
efficiency as “flags” is increased. This is the meaning of the 
ligulate ray-florets of Composites, which are either female or 
neuter, as in daisy and millefoil on the one hand, dahlia and sun- 
flower on the other. Compare in this connection the compound 
cymes of the closely allied elder and guelder rose. The former 
possesses numerous small white flowers, and, though scented, 
secretes no nectar. It is visited by insects to some extent. In 
guelder rose the outer flowers are enlarged and neuter, while the 
inner ones secrete nectar, by which many insects are attracted.” 
The same tendency is seen in some Umbellifers, as cow-parsnip 
and carrot. Here all the flowers are small, and the corollas of 
1 Ogle, in the preface to his translation of Kerner’s “ Unbidden Guests.” 
2 A cultivated variety produces neuter flowers only. Hydrangea is a 
similarly abnormal case, 
