166 THE FERTILISATION OF FLOWERS. [PART III. 
action of the insects is of as much importance to the plant as 
to themselves: for the quicker they work, the more young 
hermaphrodite flowers get fertilised in the same time, with pollen 
from male flowers or older hermaphrodite flowers; and this in 
changeable weather is an important consideration. 
I have only seen the following humble-bees visiting the horse-chestnut :— 
(1) Bombus terrestris, L.; (2) B. lapidarius, L., both species s. and ep., 
though I have heard bees humming all day long about the trees in flower in a 
neighbouring garden. My notes for visitors to this plant refer only to a single 
afternoon (May 14, 1867). The other visitors noticed were :—(3) Apis mellifica, 
L. §, s. and c.p., very ab. ; (4) Eucera longicornis, L. ¢, s.; (5) Osmia rufa, 
L. g,s.; (6) Halictus rubicundus, Christ., 2, cp. ; (7) Andrena sp. 
In &sculus Pavia (rubicunda), D.C., according to Hildebrand, 
all the hermaphrodite flowers are proterogynous, as in Aseulus 
Hippocastanum ; but the first flowers of each inflorescence are male 
only, to supply pollen for the opening proterogynous flowers (351). 
Orv. AVNACARDIACE ZL. 
Fie. 52.—Rhus Cotinus, L. 
1,—Male flower, 2.—Hermaphrodite ditto. 3.—Female ditto, n, nectary. 
88. Ruus Corinus, L. (the Wig-tree).— Rhus Cotinus shows all 
possible transitional stages between staminate, hermaphrodite, and 
pistillate flowers: the first of these are largest, most expanded, and 
most conspicuous; the last are least so. Hence most insect- 
visitors come to these flowers in the most advantageous order. 
(Cf. Ribes alpinum, Salix, Bryonia, Asparagus.) 
In both staminate and pistillate flowers of 2. Cotinus traces of 
the aborted organs remain visible. 
The flowers secrete abundant honey on the orange-red fleshy 
dise surrounding the ovaries, and display it conspicuously. 
They are visited by numerous insects, chiefly forms with short 
proboscides. Cross-fertilisation is usually effected even in the 
