Examples are the deodar of the Himalayas, the cedar of Lebanon, and that of North Africa, all very closely allied but confined to distinct areas; and the numerous closely allied species of true pine (genus Pinus), which almost always inhabit different countries or occupy different stations.

We will now consider some other modes in which natural selection will act, to adapt organisms to changed conditions.
_Adaptation to Conditions at Various Periods of Life._ It is found, that, in domestic animals and cultivated plants, variations occurring at any one period of life reappear in the offspring at the same period, and can be perpetuated and increased by selection without modifying other parts of the organisation.

Thus, variations in the caterpillar or the cocoon of the silkworm, in the eggs of poultry, and in the seeds or young shoots of many culinary vegetables, have been accumulated till those parts have become greatly modified and, for man's purposes, improved.

Owing to this fact it is easy for organisms to become so modified as to avoid dangers that occur at any one period of life.

Thus it is that so many seeds have become adapted to various modes of dissemination or protection.