The living substance of the pollen grain runs into the tip of this tube, and so is carried with it down through the style.
That the seed inherits equally from the ovule and the pollen grain is a truth that should be impressed in many ways.
Alighting on a new flower the insect rubs a pollen grain on a stigma ready to receive it, and lo!
The pollen grain is a living organism, and if it is sent in a closely corked bottle it smothers and dies.
The pollen grain is also a little sac containing protoplasm.
When the pollen grain germinates, the nuclei enter the threadlike growth (this growth is called the pollen tube; see Figure).
The pollen grain bears numerous spines, the dark spots indicate thin places in the extine.
This at once suggests the objection, how can the idioplasm, for instance, of a pollen grain be the same as that of a leaf?
At an early stage the pollen grain contains but a single cell.
Each of the 2x dwarf ovules, again, has an equal chance of being fertilised by a "tall" or by a "dwarf" pollen grain.