432 THE FERTILISATION OF FLOWERS. [PART III. 
closes the tube ; by these characters the flower becomes exclusively 
adapted for those most diligent of fertilising-agents, the long- 
proboscised bees. The palate of the lower lip is of a bright orange 
colour, forming a “ pathfinder”-; guided by this, the bee presses 
down the lower lip, and creeps so far into the tube as to be able to 
thrust its head into the wide part of the spur and then reach the 
honey. In doing this, the back of the bee comes in contact with 
the anthers and stigma ; these are matured simultaneously, and the 
stigma lies between the shorter and longer pairs of stamens, so that 
the bee can bring about both cross- and self-fertilisation. Probably, 
if pollen from another and from the same flower are applied to the 
stigma, the former outstrips the latter. In absence of insects, self- 
fertilisation is possible. The visitors consist exclusively of bees. 
Visitors : Hymenoptera—(a) Apide: (1) Apis mellifica, L. $, very ab. 
To suck, it creeps almost entirely into the flower and thrusts its head into the 
wide entrance of the spur, which it empties down to a depth of 2—3 mm. It 
creeps out again with its back covered with pollen, and proceeds more fre- 
quently to flowers at the same height on neighbouring plants than to higher 
flowers on the same. In other cases I have seen the honey-bee bite a hole in 
the spur, and empty it, as Sprengel describes. Sprengel has correctly described 
its behaviour while collecting pollen : “It slightly separates the lower lip of the 
corolla from the upper, and thrusts its head so far in as to reach the anthers 
and obtain their pollen.” (2) Bombus terrestris, L. 2, sucking normally. It 
inserts its head, thorax, and forelegs, into the flower, then thrusts its proboscis 
(7—9 mm.) almost to the tip of the spur, and emerges with the upper surface 
of its head, pro- and meso-thorax thickly covered with pollen. Sometimes it 
sweeps off part of this pollen with the brushes on its fore and midlegs, and 
places it on the hindlegs, Sprengel’s idea that the large humble-bees do not 
enter the mouth of the flower is accordingly erroneous. (3) Bombus hortorum, 
L. 9 9 and ¢. I have very frequently seen this bee empty the flowers of their — | 
honey, which ‘it can do more quickly owing to the length of its proboscis 
(17—21 mm.) than the preceding species. Even the males sometimes swept the _ 
pollen off their heads with their forelegs, and always had a number of pollen- 
grains on all their tarsal brushes ; (4) Megachile maritima, K. ¢ (8—9), s. ; 
(5) Osmia nea, L. 9 (9—10), repeatedly, s. and ¢.p.; (6) O. leucomeleena, K, 
(parvula, Duf.), 2 (24), ¢.p.; (7) Anthidium manicatum, L. 9 ¢ (9—10), ab. 
both s. and (?) ep. ; (8) Andrena Gwynana, L. ? (24), e.p.; (6) Formicide: — 
(9) Various species, ab., s. 
Delpino observed Linaria vulgaris fertilised by the hive-bee and 
by Bombus ttalicus (172). 
Linaria alpina, Mill. is likewise adapted for humblachaae but is 
visited by Lepidoptera also (609). 
Linaria minor, Desf., is very rarely visited by insects, and 
fertilises itself regularly (590, IT). 
