146 



INTRODUCTION 



It consists of stiff hairs on the tibiae, and a ' basket ' (composed of bristles arranged 

 in rows) on the basal joint of the tarsus. Among the other ' scopulipedes ' (Bombus, 

 Macropis, Anthophora, Dasypoda, Andrena, Halictus, Sphecodes) this collecting- 

 apparatus is not so perfectly developed as in the honey-bee. 



In the genus Bombus (Fig. 58, 3), for instance, the hairy investment (vide infra) 

 of the collecting-basket is not, as in Apis, converted into perfectly simple, smooth, 

 stiff bristles, placed in few rows and at tolerably equal distances, but presents a much 

 less perfect arrangement. It consists of many irregular rows of bristles, which 

 possess more or less distinct feathery branches. The collection of pollen (Hermann 



Fig. 5g. Collecting-hairs on the tibia and basal joint of the tarsus, (i) Rijjlit liindJegf of 

 Dasypoda plumipes Ps. 9, seen from behind and within. (2) The same of Panurgus Banksianus K. ?. 

 (3) The same of Podalirius bimaculatus Ps. ? ( x 7). References as in Fig. 58. 



Miiller, 'Fertilisation,' p. 53) is confined, however, as in Apis, to the outer side of 

 the hind-legs, so that the mobility of the limb is very great. The outer surface 

 of the hind-tibiae is as smooth as a mirror, and only fenced in at the edge with 

 a paHsade of long hairs, partly erect, partly inwardly curved, so as to form the 

 ' basket,' in which pollen moistened with honey can be heaped up far beyond the 

 limits of the palisade \ In this way there is not only economy of hairs and of 

 time in the process of emptying the collecting-apparatus, but the tarsal brushes 

 of the hind-legs can be used freely and without impediment. 



In Macropis (Fig. 58, i) this is not the case, for the tarsal brushes are 

 surrounded with thick balls of moistened pollen, as well as the tibiae, which are 

 clothed with relatively short collecting-hairs. 



* According to Hindenberg (Monatl. Mitt, naturw. Ver., Frankfurt a. O., vii, 1889) pollen- 

 masses on the leg of the honey-bee are, on an average, 3.5 mm. in length, and 2 mm. in breadth. 

 Should they consist of the pollen of Centaurea Scabiosa, there would be 125,000 pollen-grains in 

 each of them. The brushes on the inner side of the basal tarsal joint of the hind-leg of the bee are 

 made up of nine rows of smooth, half-erect bristles, of which there are twenty-four in the longest 

 row. The distance of the bristles from one another is c.04 mm., and therefore corresponds to the 

 size of the pollen-grains mostly collected. Investigation of the pollen-balls of a honey-bee returning 

 from the country, shows that they contain pollen-grains of only a single species of plant. 



