HOVER-FLY FLOWERS 135 
the insect alights upon another flower, to be once more deceived, the pollinium 
sticking to its head has in the meanwhile curved downwards in such a way that 
it will strike the stigma, and thus effect pollination. 
A final example is afforded by Paris quadrifolia, which has been recognized as 
a Deceptive Fly Flower by Hermann Miiller (Kosmos, ii, 1877, p. 336). The offensive 
odour at once suggests that flies are the visitors. In the middle of the flower, the 
dark purple pistil, which is crowned by four stigmas similarly coloured, shines as 
if it were wet with fluid and thus entices flies that like decomposing substances, 
e.g. Scatophaga merdaria #. To such insects the idea is suggested that here 
may be found the putrid matter they eagerly desire. The four greenish-yellow 
linear petals hang down like narrow lappets from the flower, often almost far enough 
to touch the four foliage leaves. They are regarded by Hermann Miiller (op. cit.) 
as guide-ropes for small gnats, which are led by them into the middle of the flower 
to the deceptive ovary. The erect stamens surrounding the centre of the flower, 
are thought by this investigator to serve as perches up which the flies creep, and 
so get covered with pollen. On several occasions Hermann Miiller actually observed 
a small gnat (Ceratopogon?) and a few Muscidae (among them Scatophaga 
merdaria /’.) flying to the flowers, and busying themselves chiefly with the ovary, 
Ff) ! 
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Fic. 50. Veronica Chamaedrys, L., a Hover-fly Flower. A. Flower seen from the front. B. The 
same with stamens placed together. C. The same with Ascia podagrica /., which has drawn the stamens 
together under its body, in the manner indicated in B. D. Pistil with nectaries (x 3). 
and sometimes with the stamens. But the little insects were so shy that it was 
only possible to observe them from a distance, and the entire sequence of their 
operations in the flowers could never be seen. Hermann Miiller concludes from 
his observations that at least the most important part of the process may be 
considered settled, i.e. that the pistil, although it offers no food, serves to entice 
certain Diptera, so that Paris belongs to the Deceptive Flowers. ‘This greatly 
increases the probability of the interpretation given above in respect of the floral 
adaptations of Ophrys muscifera (Kosmos, ii, 1877, p. 337)- 
E. Hover-rry Frowers (Fh). 
Hover-fly Flowers are beautifully coloured, marked by radiating streaks and 
possessing a decorative, sharply defined centre. Their delicate mechanism for 
pollination is put into action by hover-flies as elegantly coloured as themselves. 
