514 THE FERTILISATION OF FLOWERS, [PART III. 
generally be effected, but if it dces so more than once self-fertilisa- 
tion is just as likely to take place. 
A. Diptera—Syrphide : (1) Eristalis a L., freq. ; (2) E. sepulcralis, 
L., comparatively ab. ; (3) E. arbustorum, L. ; (4) Syritta pipiens, L., the 
most ab. visitor; (5) eee podagrica, F., almost as ab.; (6) Melithreptus 
scriptus, L.; (7) M. teniatus, Mgn. ; all s., the species of Eristalis and Meli- 
threptus also eating pollen. B. Hymenoptera—Apide@ : (8) Andrena dorsata, 
K. 2; (9) Halictus albipes, F. 2; (10) Prosopis armillata, Nyl. ¢; all three 
scarce, 8. C, Lepidoptera—(1 1) Pieris rapee, L., one specimen inserted its 
proboscis but flew away again at once. 
372. POLYGONUM LAPATHIFOLIUM, L., has usually five stamens, 
of which one or more are generally bent inwards and come in 
contact with the stigmas. 
Visitors: Diptera—Syrphide: (1) Eristalis sepulcralis, L., s. ; (2) Syritta 
pipiens, L., s. ; (8) Ascia podagrica, F., s. 
373. PoLYGONUM MINUS, Huds.—The flowers of this species 
are about as large as those of P. Persicaria, but form much looser 
spikes, and are therefore less conspicuous and less visited by 
insects. 
Fic. 175.—Polygonwm minus, Huds. 
1.—Flower, viewed obliquely from above. f 
2.—Ditto, in side view, after removal of the two anterior segments of the perianth. 
On a patch of P. minus and P. Persicaria in hot sunshine 
(August 16, 1871) I saw six different species of flies and two of bees 
visit P. Persicaria, while only two species of flies visited P. minus. 
As the prospect of insect-visits is smaller, those stamens which 
stand opposite to the perianth segments and which curve inwards 
persist more frequently ; ; so that flowers with only five stamens 
are rarer in P. minus than in P. Persicaria, and the flowers have 
generally six to eight stamens around a trifid style. Otherwise 
the flowers agree with those of P. Persicaria. 
Diptera—Syrphide: (1) Ascia podagrica, F., s.; (2) Syritta pipiens, 
L., s.; (3) Melithreptus pictus, Mgn., and (4) M. menthastri, L., s, and f.p, 
