102 The Naturalist in Nicaragua 
insects from obtaining access to the nectaries. Amongst 
our English flowers there are scores of interesting examples, 
and I shall describe the fertilisation of one, the common 
foxglove, on account of the exceeding simplicity with which 
this object is effected, and to draw the attention of all lovers 
of nature to this branch of a subject on which the labours 
of Darwin and other naturalists have of late years thrown a 
flood of light. The pollen of the foxglove (Digitalis purpurea) 
is carried from one flower to another by the humble-bee, who, 
far more than the hive bee, that “improves each shining 
hour,”’ deserves to be considered the type of steady, per- 
severing industry. It improves not only the hours of 
sunshine, but those of cloud, and even rain; and, long before 
the honey-bee has ventured from its door, is at work bustling 
from flower to flower, its steady hum changing to an im- 
portunate squeak as it rifles the blossoms of their sweets. 
The racemes of purple bells held up by the foxglove are 
methodically visited by it, commencing at the bottom flower, 
and ascending step by step to the highest. The four stamens 
and the pistil of the foxglove are laid closely against the 
upper side of the flower. First a stamen on one side opens 
its anthers and exposes its pollen. The humble-bee, as it 
bustles in and out, brushes this off. Then another stamen 
exposes its pollen on the other side, then another and another; 
but not till all the pollen has been brushed off does the cleft- 
end of the pistil open, and expose its viscid stigma. The 
humble-bee brushes off the pollen unto its hairy coat from the 
upper flowers of one raceme and carries it direct to the lowest 
flowers of another, where the viscid stigmas are open and 
ready to receive it. Ifthe humble-bee went first to the upper 
flowers of the spike and proceeded downwards, the whole 
economy of this plant to procure cross fertilisation would be 
upset.1 The open flower of the foxglove hangs downwards. 
The lower part, or dilated opening of the tube, is turned out- 
wards, and has scattered stiff hairs distributed over its inner 
surface; above these the inside of the flower hangs almost 
1 Darwin mentions having seen humble-bees visiting the flowering 
spikes of the Spivanthes autumnalis (ladies’ tresses), and notices that 
they always commenced with the bottom flowers, and crawling spirally 
up sucked one flower after the other,-and shows how this proceeding 
ensures the cross fertilisation of different plants.—Fertilisation of 
Orchids, p. 127. 
