112 
DARWINISM 
CHAP. 
species found in the same area. So, each part of the 
world has its own peculiar forms of pines, firs, and cedars, 
but the closely allied species or varieties are in almost 
every case inhabitants of distinct areas. 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 auy one period of life. Thus it is that so many 
seeds have become adapted to various modes of dissemination 
or protection. Some are winged, or have down or hairs 
attached to them, so as to enable them to be carried long 
distances in the air; others have curious hooks and prickles, 
which cause them to be attached firmly to the fur of mammals 
or the feathers of birds; while others are buried within sweet 
or juicy and brightly coloured fruits, which are seen and 
devoured by birds, the hard smooth seeds passing through 
their bodies in a fit state for germination. In the struggle 
for existence it must benefit a plant to have increased means 
of dispersing its seeds, and of thus having young plants pro¬ 
duced in a greater variety of soils, aspects, and surroundings, 
with a greater chance of some of them escaping their numerous 
enemies and arriving at maturity. The various differences 
referred to would, therefore, be brought about by variation and 
survival of the fittest, just as surely as the length and quality 
