224 THE FERTILISATION OF FLOWERS. [PART 1II. 
a horizontal plane, forming a disc round whose edge the stigmas, — 
directed outwards and upwards, stand. In absence of insects, self 
fertilisation may readily take place, simce the innermost stamens — 
often remain directed inwards until dehiscence has taken place. 
(2) H. sexnotatus, K., 9, cp. B. Diptera—Syrphide: (3) Eristalis arbus- 
torum, L.; (4) E. nemorum, L.; (5) Helophilus floreus, L.; (6) Syritta 
pipiens, L.-—all eating pollen. _ C. Coleoptera—Lamellicornia: (7) Trichius 
; 
Visitors: A. Hymenoptera—Apide : (1) Halictus zonulus, Sm., 2, e.p. ; 
i] 
fasciatus, L., rapidly devouring the anthers. } 
Ps 
= =. 
fog 
132. Sprraa ARuNcus, L.—The flowers of this species also are 
devoid of honey. 
i eda ae 
Visitors (in my garden at Lippstadt): A. Hymenoptera—(a) Apide: i 
(1) Prosopis signata, Pz. 2 g, f.p. ; (6) Sphegide: (2) Oxybelus bellus, Dlb., — 
f.p.; (c) Vespide : (3) Odynerus sinuatus, F., seeking vainly for honey. B. 
Diptera—(a) Syrphide : (4) Syritta pipiens, L., fip., very ab. ; (6) Muscidae : — 
(5) Species of Anthomyia, f.p. C. Coleoptera—(a) Nitidulide : (6) Meligethes, — 
ab.; (6) Dermestide: (7) Anthrenus Scrophularie, L., not rare; (8) A. 
pimpinelle, F., very ab. ; (9) A. claviger, L., scarce. 
133. SPIRHA SALICIFOLIA, L., S. ULMIFOLIA, L., S. SORBIFOLIA, 
L.—These commonly cultivated species secure very numerous 
insect-visits by their densely crowded inflorescences and their 
abundant pollen and honey. The distinctly proterogynous condi- 
tion of the flowers favours cross-fertilisation to a great extent, but — 
self-fertilisation is also provided for in case of continuous wet 
weather. -An annular, orange-coloured disk in the base of the 
receptacular tube, internal to the insertion of the stamens, secretes 
abundant honey in the form of small drops. In S. salicifolia, this 
disk has ten notches. 
Already before the flower opens, the broad stigmas are provided 
with papillze and overtop the incurved stamens. When the flower 
expands, the stamens gradually rise up, and, one by one, beginning 
with the outermost, their anthers dehisce, coating themselves all 
round with pollen. The stigmas still remain fresh, and thus, though 
at first only cross-fertilisation is possible, later on self-fertilisation 
also may take place. 
The three species grow with us in the same localities and in 
nearly equal abundance. They are visited by the same insects, and © 
I have grouped the visitors in a single list. 
A. Diptera—(a) Stratiomyide : (1) Stratiomys riparia, Mgn., s.; (0) 
Empide: (2) Empis opaca, F., ab, ; (3) E. tesselata, F., very ab. ; (4) E. 
