122 THE FLOWERING PLANT. 
field-mice, which, if left to themselves, would cause the extinction 
of humble-bees (here the pollinating insects) by demolishing 
their nests. 
Some regular flowers, however, also court the visits of special 
insects, and in these the nectar is excreted at the bottom of a 
long corolla tube, and is only accessible to the long proboscis of a 
butterfly or moth. 
An instructive comparison has been drawn between regular 
and irregular flowers in reference to the number of insect visitors. 
The following conspicuous regular flowers, with nectar easily 
reached, have the number of useful guests shown by the figures :— 
Meadow buttercup (over 60), blackberry (67), wild strawberry 
(25), hawthorn (57). In striking contrast to this are larkspur 
and monkshood (larger bees only), foxglove (3), toad-flax (about 
9 bees), early purple orchis (8). All these are conspicuous, 
irregular, and with nectar difficult to reach. 
Honey-Guides.—Many flowers are spotted or streaked with 
bright colours in such a way as to indicate the position of the 
nectar. The petals of geraniums and the lower lips of many 
labiate corollas show this. Prickles may also serve as ‘ path- 
pointers.” When intended to keep off creeping insects, they are 
generally directed downwards, while, if turned up, they may have 
the other function. Both these points are illustrated by the 
involucres of thistles. 
Honey or Nectar.—As already shown, this may be excreted by the 
most various parts. It is always situated deep down in the flower. 
Pollen.—This, as stated above, is either rough or sticky, being 
thus adapted for clinging to the bodies of insects, and at the 
same time prevented from being blown away. Where the 
arrangements for effecting crossing are simple, many stamens 
and much pollen may be present, while if these are complex the 
converse is often true. 
We will now take a few special cases in illustration of the 
points involved in cross-pollination, commencing with simple 
regular flowers, and ending with complex irregular ones. Space 
will only admit of very brief descriptions. 
I. Regular Flowers.—DButtercups are as simple here as in 
structure. Numerous small insects are attracted by the yellow 
colour, and in obtaining the nectar, are pretty sure to get dusted 
with pollen, especially as the outer stamens are matured first. 
Moderately proterandrous. 
The poppy is visited for pollen, of which a superabundance is 
formed by the numerous stamens. The broad flattened top of 
the pistil is well adapted as an alighting platform, and it also 
bears the radiating sessile stigmas, 
