ALLUREMENTS OF ANIMALS FOR THE DISPERSION OF POLLEN. 167 



which was in full flower, recorded a temperature about 2° higher than the environ- 

 ment, and probably there would have been a still greater difference if the form and 

 disposition of the capitula had not been peculiarly unfavourable to the retention 

 of the warm layer of air in immediate contact with the flowers. The inflorescences 

 of the Phlox exhibited no rise of temperature, but, on the contrary, a fall of 1'5° as 

 compared with the surrounding atmosphere, and they were copiously bedewed. 

 Thus the flies had selected a relatively warm place for their night's rest, although 

 it could not really be called a shelter. As the pollen in the Golden-rod is pushed 

 during the night out of the tube formed by the anthers, the flies found on awaking 

 next morning their meal again ready for them, and it was evidently impossible 

 that they should leave their nocturnal resting-place without first smearing them- 

 selves over with pollen. 



ALLUREMENTS OF ANIMALS WITH A VIEW TO THE DISPERSION OF POLLEN. 



Next to honey pollen is the principal food which animals seek for in flowers. 

 There are some plants from which honey is entirely absent, and which offer only 

 pollen to the food-seeking animals. Such, for example, are the Poppy {Po.paver), 

 Traveller's Joy {Clematis Vitalba), Pheasant's Eye (Adonis), and several Anemones 

 (Anemone alpina, baldensis, sylvestris, Hepatica, &c.), the numerous Cistuses and 

 Rock-roses (Cistus and HeliantheTnum), and Roses (Rosa). They all agree in this: 

 that their flowers when open stand erect and have a star-shaped or cup-like form, 

 so that the pollen falling out of the anthers is not lost, but remains for some time 

 on the concave upper surface of the petals. This is especially noticeable in flowers 

 of the Poppy family (Eschscholtzia, Olaucium, Roemeria, Argemone; cf. fig. 222 ^ 

 p. 112, and fig. 243). In comparison with the honey-producing flowers, to be 

 described later on, they always appear to have a simpler construction, which is 

 accounted for by the fact that they have no need of special contrivances for the 

 secretion and storing or protection of honey. 



The flowers of these plants are eagerly sought for by little beetles of the 

 genera Anthobium, Dasytes and Meligethes, and it is no uncommon thing to find 

 in a single Cistus or Rock-rose flower, half a dozen Dasytes greedily devouring the 

 pollen. Along with the beetles numerous flies also visit these honeyless flowers 

 for the sake of the pollen, more especially certain Ruscidse, Stratiomyidae, and 

 Syrphidse, which seize the pollen-cells with the terminal lobes of their mouth- 

 parts, bruise them thoroughly, and swallow them bit by bit. Besides these, certain 

 Hymenoptera, e.g. species of Prosopis, and also Thrips (Thrips), are eaters of pollen, 

 and if they establish themselves in great numbers can in a short time almost 

 entirely clear away all there is to be found. 



It is well known that bees and humble-bees collect pollen in large quantities 

 and carry it to their nests as food for the larvae. The collecting is carried on by 

 means of specially constructed hairs and bristles, which clothe various parts of the 

 body, particularly the abdomen and the terminal segments of the hind-legs, and 



