PART III. ] THE MECHANISMS OF FLOWERS. 533 
portions of pollen may be accidentally carried away by minute 
insects, but the flower is self-fertilised in a still more conspicuous 
degree than #. microphylla. I have described elsewhere (565) 
the changes in the relative position of anther and stigma which 
render self-fertilisation possible, and the intermediate nee 
between the above-mentioned species of Hpipactis. 
Epipactis palustris, Crantz.—Mr. W. E. Darwin saw this species 
visited and fertilised abundantly in the Isle of Wight by Apis 
mellifica, % ; also by flies (Sarcophaga carnosa and Celopa frigida) 
and by Crabro brevis. 
Epipogon Gmelini, Rich—Paul Rohrbach! has described the 
structure and fertilisation of this flower very admirably (675). : 
He observed Bombus lucorwm, L., visiting the flowers. 
Tribe Ophrydee. 
Serapias longipetala, Pollin., is visited by bees in the west of 
Liguria (Delpino, 567). 
Herminium Monorchis, R. Br—George Darwin observed the 
flowers visited by twenty-seven species of small insects, of which 
the largest were one-twentieth of an inch long. They consisted 
of Hymenoptera (especially Tetrastichus diaphanthus and 
Pteromalini), Diptera, and Coleoptera (e.g. Malthodes brevicollis). 
I have found the flowers visited on the Alps by small Braconidz 
and Pteromalidz (609). 
Platanthera—I have elsewhere (565) proved at very consider- 
able length that the varieties distinguished as P. bifolia and 
P. chlorantha by German botanists are connected with one another 
by numerous intermediate forms; but that the plant referred to 
by Darwin as P. bifolia corresponds to P. solstitialis, Bonningh., 
and is a well-defined species. The spur of P. solstitialis is from 
12°to 21 mm. long, that of P. chlorantha from 23 to 43 mm.; in 
both species the spur is too narrow to admit a bee’s proboscis. 
The honey is therefore accessible only to Lepidoptera, and in. the 
extreme forms of P. chlorantha only to Sphingidw. The colour 
of the flowers suggests that they are adapted for nocturnal and . 
crepuscular insects. Darwin caught a specimen of Hadena dentina 
to one of whose eyes a sticky disk of P. chloran'ha was attached, 
and a Plusia with one attached to the margin of its eye. The 
sticky disks stand much closer together in P. solstitialis, and 
1 This able and brilliant naturalist died at an early age. 
