62 NEW ZEALAND NATURE-STUDY BOOK 
sends out a pollen tube; these grow down the pistil and 
reach the ovary. Here each one finds its way to an ovule, 
‘and enters the ovule through a small opening (the 
micropyle). The living matter of the pollen tube then 
fuses with that of the ovule and fertilisation is secured. 
Pollination. The transference of the pollen from the 
anthers to the stigma is known as pollination. The 
simplest form of pollination is when the pollen is transfered 
from the anther to the stigma of the same flower. ‘This is 
known as self-pollination, and such a flower is said to be 
self-pollinated. When, on the other hand, the pollen from 
one plant finds its way to the stigma of a flower growing 
on another plant of the same kind, it is said to be cross- 
pollinated. | 
It has been proved that cross-pollination. results in 
producing a larger yield of seed, and moreover, séed which 
grows into larger and healthier plants. Hence it is highly 
desirable that cross-pollination should take place, and various. 
arrangements exist in flowers for bringing this about. A 
detailed account of these arrangements would ‘be beyond 
the scope of this work. The following, however, may be 
mentioned. Sometimes the stamens and pistil do not occur 
on the same plant—well seen in the staminate and pistillate 
flowers of the Clematis and Bush-lawyer, which grow on 
separate plants. Then again, cross-pollination is brought 
about in the case of many plants having both staminate 
and pistillate flowers on the same individual—by the agency 
of insects attracted by the brightly coloured blossoms, by 
the perfume, or by the sweet nectar possessed by many 
plants ; bees and other insects fly from flower to flower and __ 
in doing so carry the pollen from one plant to anothér.’ If 
a bee be watched visiting the blossoms of a Pea-plant:the 
whole process can be observed ; the insect alights on’ the 
‘(wings” of the flower and its weight lowers these and 
