Mar. 15. 1912 



173 



and at the same time forces it out to the 

 lower end of the corbicula, which is here 

 shghtly depressed and ahnost devoid of hairs. 

 Tlie compression of the pollen in the re- 

 ceiver is an essential i)art of the process; for 

 loose pollen grains such as occur on the met- 

 tatarsal brushes would not hold together in 

 the corbicula. In the bumblebee the angle 

 between (he surface of the receiver and that 

 of the corbicula is obtuse, and thecompress- 

 ed pollen easily passes from the one to the 

 other; but in the honeybee there is a sharp 

 angle at the corner, and the auricle bears a 

 fringe of hairs (/') to guide the stream of 

 pollen to the corbicula; also the honeybee's 

 auricle is evidently pressed back by the pol- 

 len, for it has no other means of escape. 



Fig, 1.— Juncture of tibia and metatarsus in hind leg of worker honey' 

 bee, outer side. 



Fig. 2. — Diagrammatic section of the same, showing mode of conveying 

 pollen. 



a, metatarsus: b. tibia; c, comb: d, receiver for pollen: e, auricle: /, 

 fringe of hair on auricle. 



I forced a queen bumblebee to relax, and, 

 after placing some pollen obtained from a 

 comb taken out of one of my hives in the 

 receiver, I straightened the leg. The pollen 

 was immediately delivered to the corbicula. 

 I was struck with the freedom of action of 

 the joint, and noticed that the auricle could 

 be placed in the receiver in various positions, 

 so that it can not only compress pollen 

 there, but it can scrape out the receiver, 

 and, on the other hand, can deliver the pol- 



len high up on the corbicula. In the honey- 

 bee the joint works still more freely. The 

 fact that, in the bumblebee, the pollen 

 always begins to collect at the apical end of 

 the corbicula, is now clear, and we see why 

 the corbicula is so smooth and bare, for the 

 pollen actually slides up it. 



It is a significant fact that, although the 

 corbicula is surrounded with a fringe of stiff 

 hairs which act, as Cheshire observes, like 

 the stakes that the farmer places round the 

 sides of his wagon when he desires to carry 

 hay, this fringe is interrupted at the spot 

 where the receiver discharges its pollen on 

 the corbicula. In the bumblebee the en- 

 trance here to the corbicula carries only 

 about three stiflf hairs. These hairs are short 

 3^^ and upright, and widely 



separated from one an- 

 other, and are some lit- 

 tle way inside the en- 

 trance. It is evident 

 that their function is to 

 provide a means of at- 

 tachment for the pollen 

 until the lump has 

 grown large enough to 

 be enclosed between the 

 hairs at the sides of the 

 corbicula. The entrance 

 to the corbicula is, in the 

 bumblebee, densely dot- 

 ted with fluff (under the 

 microscope mossy hairs) 

 which also probably 

 help to hold the pollen. 

 In the honeybee there 

 are no stiff hairs, and 

 very little fluff in the en- 

 trance to the corbicula. 



In the bumblebee the 

 long hairs on either side 

 of the entrance to the 

 corbicula form a wide 

 and shallow arch over 

 it. The object of this 

 arch is, no doubt, to 

 help to support the 

 lump of pollen on the 

 corbicula without inter- 

 ferring with the passage 

 of fresh pollen to the 

 corbicula. The arch also 

 helps to guide the pol- 

 len to the corbicula. In 

 the honeybee the arch is 

 less pronounced, and 

 consists chiefly of hairs 

 from the lower side, and 

 these are so long as to 

 stretch almost across the tibia. 



These facts add an interesting page to 

 the wonderful story of the bee that is not 

 given in our text books. How often have 

 we seen the bees humming around the 

 flowers, busily scraping their dangling legs 

 together, and every now and then giving 

 them a little jerk! At each jerk a minute 

 quantity of pollen is tucked up on the cor- 

 bicula. 

 On examining the workers of several spe- 



