PHYSIOLOGY OF THE FLOWER I 1 9 



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, . . . " l 



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. 



Gonspicuousness. — The corolla, calyx, bracts, and even the 

 flower-stalk, may all display more or less colour. In the simpler 

 flowers yell oics are displayed, which seem attractive to small 

 insects and beetles. White 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. Red 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 flowers 

 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 especially is 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. 2 

 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. 



