. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. I02 ANGIOSPERMAE—DICOTYLEDONES protected from rain by closure of the corolla during dull weather. This also takes place at night. The inner side of the corolla possesses nectar-guides in the form of small whitish circles with brownish centres, from which alternating blue and whitish longitudinal streaks turn to the base of the flower. At about its middle the corolla- tube suddenly contracts, and from this point downwards it, and the filaments fused with it,
. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. I02 ANGIOSPERMAE—DICOTYLEDONES protected from rain by closure of the corolla during dull weather. This also takes place at night. The inner side of the corolla possesses nectar-guides in the form of small whitish circles with brownish centres, from which alternating blue and whitish longitudinal streaks turn to the base of the flower. At about its middle the corolla- tube suddenly contracts, and from this point downwards it, and the filaments fused with it, closely surround the ovary. Humble-bees can creep half-way into the flowers, dusting themselves in younger ones from the dehisced anthers which closely surround the still immature stigmas. In older flowers the style has elongated and its stigmatic branches have become bent back so that their papillose inner surfaces will be touched by those parts of humble-bee visitors which have taken up pollen. The arrange- ments, in fact, are such that insects of a size proportionate to the interior of the flower inevitably ef- fect crossing. Kerner states that automatic self-pollination is pos- sible in later stages of anthesis, for when the flower closes some of the pollen still clinging to the an- thers is transferred to the internally project- ing folds of the corolla, and is subsequently raised to the level of the stigma by elongation of the corolla-tube. Closure will then effect auto- gamy. Warnstorf de- scribes the pollen- grains as yellowish in colour, ellipsoidal, with a groove, delicately papillose, striated, on the average 50 fi. long and 25 /a broad. Visitors.—E. MoUer sent me the following from Sylt, of which only Nos. i, 2, and 5 were able to get at the nectar ('Weit. Beob. u. Bl. u. Insekt. a. d. nordfr. Ins.,' p. 238).— A. Hymenoptera. Apidae: i. Bombus cognatus Steph. 5 and 5, skg.; 2. B. derhamellus K. 5, do.; 3. B. terrester Z., stealing nectar (up to beginning of Oc
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