parti) THE MECHANISMS OF FLOWERS. 305 
perfect, for many of the long stamens do not twist properly, and 
to a great extent waste their pollen. 
 Posoqueria (Martha) fragrans, Roxb. has been described by my 
_ brother Fritz Miiller (549).? It affords a most remarkable example 
_of adaptation to Sphingidz. The white colour of the flowers, their 
strong perfume, the long, narrow tube 11 to 14 em. long, all point 
it out as such. The abundant honey at the base of the tube can 
only be reached by the tongues of Sphingidew; and only these 
insects, ¢.g., S. rustica, L., whose proboscis is 15 mm. long, have 
been seen to visit the flower (F. Miiller, Oct. 1873). 
_ The five exserted anthers are united into an oval knob directed 
obliquely downwards and containing the loosely coherent pollen 
which escaped from the anthers before the expansion of the flower. 
The filament of the inferior stamen possesses a very great elastic 
tension acting upwards, those of the superior and lateral stamens 
have a similar tension outwards. The insect’s proboscis has only 
one available point at which to enter the flower, and when in doing 
so it touches one of the superior stamens at a certain spot the 
tension of the filaments is released. "The inferior stamen springs 
up with such violence that it hurls the loosely coherent pollen 
against the insect’s proboscis at an angle of 50° with the tube of 
the corolla, and with an initial velocity of about 3 mm. per 
Second ; at the same time it closes the entrance of the tube. The 
superior and lateral stamens spring at the same time to the sides, 
the empty anthers of a superior and a lateral stamen remaining 
coherent on either side. About twelve hours afterwards the 
inferior stamen extends itself again and leaves the entrance to the 
honey open once more. If a hawk-moth, after exploding a flower 
in the male stage, comes to one in the stage under consideration, 
it is repaid for its startling reception in the former case by a rich 
supply of honey ; and in thrusting its pollen- -dusted proboscis down 
(0 the base of the flower it brings it in contact with the stigma 
which stands in the middle of the tube. 
_ My brother, in his paper on Faramea (554), refers again to 
f = osoqueria, and points out that most of the flowers (whose only 
: fertilisers are abroad in the evening) open towards evening, but 
% that a considerable number open at various hours of the day, 
ractimes even in early morning, and that these are exploded 
by diurnal insects which cannot effect fertilisation. This is 
1 4a Grifuuhia Fragrans, W. A. 
__ ? Darwin wrote tome: ‘ Your brother s paper on Martha i is, I think, one of the - 
, 4 ost wonderful ever written.’ 
4 x 
