Chapter 6. 
SEEDS AND SEEDLINGS. 
Vitality and longevity of seeds. Conditions favouring germi- 
nation. Seedlings. Variation. Natural and artificial selection. 
Sports or mutations. Hybrids and the laws of heredity. 
Ripe seeds are surrounded by a hard seed coat which is 
more or less impervious and prevents complete drying up 
of the embryonic plant within the seed. The more re- 
sistant the coat the longer the seed can preserve its vzzality. 
The seeds of some plants germinate almost immediately 
they are mature, but most of them are adapted for and 
require a period of rest. During that time it is necessary 
to keep them dry and fairly cool. Under such conditions 
they can preserve their power of germination for some 
years, though a certain number even of resistant seeds will 
die. It is also more difficult to germinate old seeds, owing 
probably to the drying of the seed coat, as well as to 
changes which have taken place in the living cells of the 
seed. When kept dry little alteration takes place 
internally, and the seed can remain dormant, practically 
no loss of matter taking place by respiration. For what 
length of time this suspension of animation can last is not 
definitely ascertained, but we may say with certainty that 
we have no proof that seeds which have lain dormant for 
a thousand years or more, like those which have been taken 
from Egyptian mummy cases, can be germinated. That 
so-called mummy wheat and mummy peas have been 
originally obtained from Egyptian mummies must be re- 
garded as purely legendary. Accurate investigations 
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