ie ART 11. THE MECHANISMS OF FLOWERS. 377 
ie sorolla. A honey-seeking insect, immediately after touching the 
ia ‘stigma, brings its proboscis in contact with some of these append- 
es, whereupon a shower of dry, dusty pollen is shed from, the 
Picks i in the anthers on to the forepart of the insect’s head. 
iP. In absence of insects, self-fertilisation may take place, as part of 
_ the pollen always falls upon the edge of the stigma and remains 
adherent there. Humble-bees are the chief fertilising agents. 
_ This species was described by Dr. Ogle in No. 633. 
_ <A, Hymenoptera—Apide: (1) Bombus senilis, Sm. 2? § ¢ (14—15) ; (2) 
|B. silvarum, L. 9 $ (10—14) ; (3) B. agrorum, F. 2 § (10—15); (4) B. 
 Rajellus, Ill. § (10—11) ; (5) B. terrestris, L. 9 (7—9), all very ab., hanging 
- to the corolla back downwards ; (6) Nomada Solidaginis, Pz. ¢, I saw this 
_ insect once, apparently trying in vain to reach the honey ; (7) Apis mellifica, 
_L. $,is scarcely able to reach the base of the flower legitimately, as its 
_ proboscis is only 6 mm. long. It is a very abundant visitor of Erica tetralix, 
but usually bites through the corolla, about midway. On Oct, 15, 1871, 
_ J saw numerous honey-bees sucking normally. I omitted to observe whether 
these late flowers were a little smaller than those of summer ; if so they would 
exactly suit the honey-bee. B. Diptera—Syrphide: (8) Volucella bombylans, 
L. (7—8), ab., s.; (9) V. plumata, L. freq., s. ; (10) V. hemarrhoidalis, Zett., 
scarce, s. C. Lepidoptera—Noctue : (11) Plusia gamma, L., s. 
Erica cinerea, L., the fine-leaved heath, agrees in the structure 
of its flower with JL. tetralix, according to Dr. Ogle (633). 
Erica carnea, L.—This species is adapted by the colour and 
size of its flowers to butterflies, which alone (e.g. V. carduz) visit 
it in abundance, and effect cross-fertilisation, The sepals and 
petals vary from bright pink to crimson, and the peduncles are 
still more intensely coloured. The flower narrows so much towards 
its mouth that the entrance is blocked by the anthers, and just 
admits the thin proboscis of a butterfly, which cannot avoid touching 
first the stigma and then the anthers, and so performing cross- 
_ fertilisation. I have seen Bombus terrestris making great but 
ineffectual efforts to insert its proboscis into the flower. The 
- inverted position of the flower is somewhat inconvenient for butter- 
flies, and causes them delay. We may suppose that the ancestors 
of Erica carnea grew where bees were more plentiful and butter- 
flies less so, and that the flowers were first adapted for bees, 
as almost all other inverted, bell-shaped flowers are; and that 
_ they acquired their present colour and form under the influence 
| of Lepidoptera, which preponderate so conspicuously in the Alps 
(609). 
287. CALLUNA VULGARIS, L—The bell- -shaped corolla is 2 to 
ee 
