56 
TOPULAR SCIENCE REVIEW. 
It is a tube of double structure, each half being easily se- 
parated or closed at pleasure by the fly ; when not used it 
is nicely coiled up under the chin. When needed for 
sucking the juices of plants it is uncoiled, and, the two half 
tubes being kept together by neat little teeth interlocking, 
the tube draws up the juice into the mouth of the fly. To 
enable it to do this, each half of the tube is furnished with a 
multitude of fibres or nerves, which are reticulated across 
from side to side, making it easily compressible. The air is 
exhausted in the tube by this compression, and its place is at 
once filled by the juice which rises in the tube. Figs. R and 
s show the general appearance of the tube, fig. t the re- 
ticulated fibres for exhausting the air. Near the point of the 
trunk, an additional means of suction is probably furnished by 
a number of little protuberances, like nipples, which no doubt 
help to draw up, like a sponge, by capillary attraction, the 
juice when only in small quantities. These, however, do not 
seem to be perforated with suction holes : even when photo- 
graphed with the microscope on a large scale, they show no 
sign of any channel through them. 
This trunk is, in use, thrust into the nectary of flowers, 
and in its passage is often covered with pollen. Hence, those 
butterflies which flit from flower to flower indiscriminately, 
such as the Peacock or Admiral, would be likely to carry from 
one flower to another pollen grains, of a useless or different 
kind, which might interfere with the proper fructification of the 
flowers they are brought to. Now here comes in one of those 
wise adaptations of the insect to the vegetable world, which 
proves the superintendence of one Master Mind. Such 
butterflies are furnished with a long pair of soft brushes, 
instead of their forelegs ; with which, while using the two 
other pair of legs to support themselves, they wipe and clean 
their trunks after each time of using. So that all adhering 
pollen is wiped off, and not carried to other plants where it is 
not needed. 
In other insects, such as the bee, the provision for preventing 
pollen mixing is accomplished by a beautiful instinct, which 
leads the bee to keep only to one class of flower in each trip 
it takes for honey. 
But the butterfly having no settled home, spends its little 
life in roaming anywhere ; and hence has this modified change 
of legs into brushes, as seen at fig. b. 
Its roaming seldom lasts much longer than necessary to 
4 meet some mate, and deposit the eggs, like carved ivory balls, 
as at fig. c, on the plant which will be best fitted for nourish- 
ing its young when hatched. 
The life of one that has not yet met its mate may be pro- 
