[282] It is a modification of the upper stigma.
[283] This rather obscure statement may be paraphrased thus:—
The machinery is so perfect that the plant can afford to minimise the amount of pollen produced. Where the machinery for pollen distribution is of a cruder sort, for instance where it is carried by the wind, enormous quantities are produced, e.g. in the fir tree.
[284] "Darwin considéré, &c.," Archives des Sciences Physiques et Naturelles 3ème période. Tome vii. 481, 1882.
[285] May 24th, 1862.
[286] June 14th, 1862.
[287] My father's "Prefatory Notice" to this work is dated February 6th, 1882, and is therefore almost the last of his writings.
[288] See Autobiography, p. 48.
[289] The pollen or fertilising element is in each species adapted to produce a certain change in the egg-cell (or female element), just as a key is adapted to a lock. If a key opens a lock for which it was never intended it is an incidental result. In the same way if the pollen of species of A. proves to be capable of fertilising the egg-cell of species B. we may call it incidental.