ARUM MACULATUM AND ITS CROSS-FERTILIZATION. 268 
Arums ‘7 Chiselhurst, aud brought him one, exclaiming, “ This 
thing in the middle is quite hot.”” He continues—‘ Finding that 
the alate continued the whole of that and put of the next day, 
I tested it by applying both the spadix and spathe to the bulb of a 
good thermometer, and found that the clubby ri of the spadix 
» was 71° Fahr.. whilst the spathe only 573°, making a difference of 
1BgP” Avs athe seems to catch its full sore: ef of flies 
very seca ergs they begin to enter as soon as ever the 
As it deers Sores that they are attracted by the scent, 
perhaps assisted by the spadix (Sir John Lubbo nf makes no 
mention of the heat or smell, but says they enter “attracted 
y the showy central spadix, the prospect of shelter or of honey’’), 
fall rrakiis that they must all be caught within a very short space 
he imprisoned flies a probably (as will hereafter be 
shown) brought pollen from some other Arum, which they are 
sure to deposit on the bic of the stigmas whilst crawling 
about them orp? in the bottom of the bulb, up the sides of 
which they ar able to climb, and thus the eross- fertilization 
of the plant is  abeeinphieben! These flies are peculiarly adapted 
for the carriage of pollen, having very hairy bodies and wings ; 
so that under the microscope they wa often be seen to be covered 
with om 
a small round hole. The ovules are now of course incapable of 
receiving any further fertilization, having received the great ad- 
vantage ge rossing; and hereafter we shall give reasons for 
believing that this species has lost the power of self-fertilization. 
At this stage a minute drop of liquid exudes from the hole in the 
tip of each ovary, and as we have sometimes seen flies greeny 
eter ig this it is ane of the nature of nectar, Shortl Feed 
covered with it. We do not know any use for the lower circle of 
hairs, which are always more or less rudimentary, unless they 
are-to prevent the flies climbing up to the anthers and the space 
abo - a where they would not receive the shower of pollen. 
A 
up, etd the flies, escaping, carry the pollen away to some 
