150 INTRODUCTION 
trace of feathery branching. ‘The abdominal collecting-apparatus of one division of 
the bee family stands in sharp contrast to the collecting-apparatus developed on the 
hind-legs of the other division, not only in the structure of its hairs, but also in 
the way it is used. The pollen-collecting apparatus of the latter consists of a forest 
of feathery hairs, into which the tarsal brushes (formed of simple stiff bristles) sweep 
the pollen they have scraped off. In the present group, on the other hand, 
the pollen-collecting apparatus is a large brush of simple rigid bristles, and this 
itself sweeps up the pollen. ‘That this difference of function, to which the difference 
of structure points, actually exists, is thoroughly confirmed by observing the visits 
which the dasygastres make to flowers. For more than nine-tenths of the flowers visited 
by bees with abdominal brushes are such as are adapted to dust the ventral surface 
of the bee with pollen (Echium, Papilionaceae, Compositae, and so forth), so that the 
ventral collecting-apparatus is frequently completely filled with pollen without any 
help from the tarsal brushes. On the heads of Composites, for example, dasygastres 
may be seen rapidly thrusting their tongues ifto one floret after another for the 
purpose of getting nectar, meanwhile turning the body half or entirely round, so that 
the pollen lying loose on the surface of the head is forced between the hairs of the 
abdominal brush. This is quite full after a few heads have been visited. In this 
way Hermann Miiller very frequently saw, for 
example, Megachile lagopoda Z. upon Onopordon 
Acanthium, and Osmia spinulosa X. upon Car- 
duus acanthoides. More rarely bees of this 
group gather pollen on flowers which deposit 
it on their backs. In such cases they use their 
tarsal brushes to remove pollen that remains 
sticking among the feathery hairs that cover 
UES their bodies, and bring it to the abdominal brush. 
(after Herm. Miller). (1) Abdomen of Osmia Hermann Miiller Saw, for example, Anthidium 
spinulosa .., seen from below. (2) Sideview manicatum J. behaving in this way on the 
of the same (X 7). 
flowers of Ballota nigra. 
The abdominal collecting-apparatus is similarly formed in bees belonging to 
different genera, while, as shown above, the collecting-apparatus on the hind-legs 
exhibits gradual specialization, step by step, from Prosopis to Apis. It is also 
possible to recognize a series of adaptations in the mouth-parts having reference to 
getting nectar from flowers. Hermann Miiller describes these (‘ Fertilisation,’ pp. 48- 
64) somewhat as follows :— 
When at rest (Fig. 64, 1) the lower mouth-parts, i.e. maxillae and labium 
(under lip), are withdrawn in Prosopis into a cavity on the under-side of the head, 
which they exactly fill, and this is effected by means of the folding together of stiff 
chitinous parts, which are united by movable joints. The two basal pieces or 
cardines of the maxillae (Fig. 64, 4, cc) are jointed into two sockets at the sides of 
the cavity under the head, in such a way that they can rotate either forwards or 
backwards. When at rest they are folded back, drawing with them the stipites 
(stems) of the maxillae (Fig. 64, 1, 2, 3, 4, s¢), which are movably articulated to 
their distal ends, and also the mentum (m/), which is fastened between them, the 
result being that they are completely covered by these structures. The laciniae of 
2 
