PART 111] THE MECHANISMS OF FLOWERS. 165 
_ drawings of the horse-chestnut flower, made before I became 
- acquainted with Sprengel’s work, differ in one point from his 
- account, and agree with that of Hildebrand. While Sprengel 
_ declares that in the younger flowers insect-visitors come in contact 
only with the stamens because the style is as yet low down, I 
found just the opposite condition, as the annexed figures show. 
_ Although I neglected to compare microscopically stigmas of younger 
_and older flowers, I can hardly doubt that Hildebrand is right 
in stating the hermaphrodite flowers of the horse-chestnut to be 
_ proterogynous. According to Dr. Ogle (632), there occur usually 
_ in the lower part of each inflorescence flowers whose anthers fall 
_ off without dehiscing although their loculi are full of pollen, and 
_ which thus play the part of purely female flowers. 
| The chief fertilisers are humble-bees ; therefore the dimensions 
‘ of the flower are just such as to suit dine insects. The style 
Fig. 51.—A4sculus Hippocastanum. 
1.—Section of male flower. 
2.—Hermaphrodite flower in first (female) stage, seen obliquely from the front. 
3.—Section of ditto, in second (male) stage. 
a, anther ; n, nectary ; ov, ovary ; ov’ rudimentary ovary ; 8, sepal; p, petal. 
and stamens protrude so far from the flower (in a curve concave 
superiorly), that a bee on alighting just touches stigma or anthers 
_ with the hinder part of his body. The legs fit into the interspaces 
__ between the petals, so that the insect finds itself at once in the 
most convenient position for sucking, and immediately thrusts 
its proboscis in the direction 2 (1, 3, Fig. 51) into the honey- 
_ holding base of the flower. Such a position also permits the 
insect to fly away very readily, and thus the whole time occupied 
is reduced to a minimum: alighting, thrusting in the proboscis, 
| and flying away again is the work of a few seconds. 
_ Other bees, whose dimensions do not correspond so well to 
those of the flowers, have to spend more time over the operation. 
The humble-bee is also favourably placed for carrying off pollen 
; on the tarsal brushes of the middle and hindlegs. The quick 
Be 
