2i8 ANGIOSPERMAE—DICOTYLEDONES 



corolla-tube is 9-10 mm. long, and therefore only accessible to humble-bees with 

 a long or medium proboscis. Short-tongued humble-bees perforate the flowers and 

 steal the nectar. The four anthers lie in the helmet-shaped upper lip, and are united 

 into a sprinkling-apparatus. Each anther is so closely apposed by its margins to the 

 corresponding one on the other side, and dehisces so completely on this surface that 

 the two together make a single pollen receptacle, and interwoven hairs make the 

 closure of this more complete. The two receptacles are borne on stiff filaments of 

 which the anterior ones converge below and are beset with sharp points on their inner 

 sides, but their upper parts are quite smooth, and sufficiently far apart to permit 

 a humble-bee to conveniently insert the end of its proboscis. When the bee forces 

 its way further it separates the filaments, and thus opens the receptacles so that pollen 

 falls directly upon its proboscis, dispersal at the side being prevented by the hairs on 

 the lower edges of the anthers. 



The style is closely apposed above to the inner surface of the upper lip, and 

 projects so far out of the flower that the stigma is always first touched by humble-bee 

 visitors, rendering cross-pollination inevitable. Such visitors are very numerous, for 

 the racemose inflorescences are tolerably conspicuous, the effect being heightened by 

 the pale bracts. The style projects straight out of the flower to the end of anthesis, 

 and even elongates, so that automatic self-pollination is impossible. Warnstorf 

 describes the pollen-grains as white in colour, spheroidal when examined in water, 

 smooth, about 56 m. in diameter. 



Visitors. — Herm. Miiller observed 9 humble-bees. — 



1. Bombus hortorum L. 5 and 5 (proboscis 19-21 mm.), skg. legitimately; 

 2. B. hypnorum Z.J (prob. 10-12 mm.), skg. legitimately and po-cltg. ; 3. B. 

 muscorum F. 5 and 5 (prob. i4-r5 mm.), do.; 4. B. pratorum L. 5 (prob. 8 mm.), 

 skg. by perforation, and po-cltg.; 5. B. rajellus K. 5 (prob. 12-13 nim.), skg. 

 legitimately; 6. B. sylvarum Z. 5 and 5 (prob. 10-14 mm.), do. ; 7. B. scrimshiranus 

 K. 5 (prob. 10 mm.), do. ; 8. B. terrester Z. 5 and 5 (prob. 9 mm.), po-cltg. and skg. 

 by perforation; 9. Psithyrus barbutellus K. 5 (prob. 12 mm.), skg. legitimately. 



The following were recorded by the observers, and for the localities stated. — 



Sprengel, bees and humble-bees. Knuth (Schleswig-Holstein), 4 humble-bees — 

 I. Bombus hortorum Z. 5, skg. legitimately; 2. B. cognatus Steph. J; 3. B. der- 

 hamellus K. ^; 4- B. distinguendus Mor. 5: (Riigen), 2 humble-bees (Bombus 

 hortorum Z. 5, skg., and B. terrester Z., stealing nectar) and the honey-bee, steaHng 

 nectar. Alfken (Bremen), 3 humble-bees — i. Bombus arenicola Ths. j; 2. B. 

 derhamellus K. ; 3. B. sylvarum Z. j. Schletterer and von Dalla Torre (Tyrol), 

 Bombus derhamellus K. H. de Vries (Netherlands), the humble-bee Bombus sub- 

 terraneus Z. 5 (Ned. Kruidk. Arch., Nijmegen, 2. Ser., 2. Deel, 1875). MacLeod 

 (Flanders), the humble-bee Bombus hortorum Z. : (Pyrenees), a moth (Plusia sp.) and 

 6 humble-bees, skg., also the humble-bee Bombus mastrucatus Gerst. as a nectar-thief 

 (Bot. Jaarb. Dodonaea, Ghent, iii, 1891, pp. 313-14). Scott-Elliot (Dumfriesshire), 

 3 humble-bees ('Flora of Dumfriesshire,' p. 132). 



Kirchner (' Flora v. Stuttgart,' p. 599) describes as a distinct species the var. 

 hirsutus AH., and states that its flower mechanism agrees with that of the main type. 

 But Hermann Miiller (' Alpenblumen,' pp. 289-91), in his account of Rhinanthus 

 Alectorolophus Z., which is identical with the above, says that its flowers are equally 

 adapted to humble-bees and Lepidoptera. They possess, in fact, a ' Lepidopterid 

 door ' immediately under the stigma, through which a visiting Lepidopterid can insert 



