544 Transactions.— Botany. 
as follows :—The fly alights on the front of the corolla, which forms an 
excellent landing-place, and creeps a little way into the flower, at the same 
time bending down its head, so.as to reach with its proboscis the nectar 
at the base of the style. If the visitor be of the right size (a species 
approaching the common house-fly in this respect seems to suit the require- 
ments of the flower the best), it will inevitably strike its head against the 
bent summit of the indusium. Should the flower have been expanded for 
some time, probably nothing will be effected ; but should it be one in which 
the stigma is thrusting the pollen out of the indusium, the insect cannot 
fail to get the back and front of its head plentifully dusted over with pollen. 
Let it now visit another and older flower, and it is evident that when occupy- 
ing the same position as before, that the part of its head which had then 
rubbed against the extremity of the indusium, will now strike against the 
stigma, which, as we have seen, protrudes beyond the indusium when 
mature. In this ease the pollen would adhere to the viscid papille with 
which the stigma is covered, and fertilization would be ensured. 
If this view of the fertilization of the plant be accepted, we can readily 
see the meaning of several facts that would otherwise remain without ex- 
planation. For instance, the sudden and elastic movement which the 
stamens make to the back of the flower immediately after expansion, is 
probably of use by removing them from a position in which they would 
interfere with the attempts of insects to reach the nectar. Similarly, the 
bending of the upper part of the style—also taking just before or at the 
opening of the flower—evidently happens for the purpose of turning both 
the indusium and stigma towards that part of the flower on which insects 
most often alight; while the few weak hairs that are found on the outside 
of the indusium—a point of structure that might well at first sight appear 
to be of little or no use in the economy of the plant—are probably of im- 
portance as serving to detain some of the pollen after it has been pushed 
out of the indusium in the very best position for the visits of insects that it 
could possibly have occupied. 
To any one possessing a better knowledge of entomology than I do, it 
would be an interesting study to catalogue the various insects that visit this 
plant. In Europe this has been done for several plants by the distinguished 
naturalist, Herman Müller, and with very surprising results, as many as 
60 different species having been observed to visit one Ikind of flower, while 
others, to all appearance equally attractive, are restricted to a much smaller 
number of visitors. In the case of Selliera, Diptera seem to be most fre- 
quently seen about the flowers, some twelve or thirteen distinct species 
having been observed, some of which, however, are of small size, and but 
poorly fitted for the work of transporting the pollen. Two or three Hymen- 
