160 BOTANY 
is from the body formed by this fusion of the pollen 
nucleus with the egg cell that the embryo develops. It 
is necessary here to distinguish the terms pollination 
and fertilization. Pollination occurs when the pollen 
grain reaches the stigma, but fertilization does not 
take place till the pollen nucleus fuses with the egg 
cell. To investigate the latter process would need a 
microscope and is therefore beyond our scope. 
Pollination, however, is well within our range, and 
forms one of the most fascinating branches of the 
science of botany. 
Nectaries—Though insects are attracted to the 
flower by its size, shape, colour, and perfume, it is in 
the expectation of obtaining nectar that their visits 
are actually made. This nectar is a sweet fluid pro- 
duced by nectaries, which are little swellings that may 
arise in almost any part of the flower. In the 
buttercup, for instance, the nectary is at the pointed 
base of the petal, while, in the wallflower, it is where 
the stamens spring from the receptacle. A profusion 
of nectar is produced by many native plants, among 
which may be mentioned the flax, fuchsia, rewarewa, 
and pohutukawa. In some flowers, such as the iris 
and pansy, there are markings that point out the way 
to the nectaries. These are the so-called honey guides. 
Nectaries are always so situated that when the proper 
insect secures the nectar they secrete, it must of neces- 
sity also accomplish or take a step towards accom- 
plishing the work of pollination. 
Adhesion and Cohesion (Fig. 105).—In some 
flowers, parts that must originally have been free have 
erown together. This has already been noted in the 
ease of the earpels of the lily and violet, as well as in 
the corolla of the foxglove and calyx of the bean. 
Where the union is, as in the cases mentioned, between 
members of the same whorl, we have what is called 
cohesion. Where, however, the union is between 
