296 
A TEXTBOOK OF GENERAL BOTANY 
fruit, the radicle finally becomes caught in mud, and the growth 
of the seedling continues (Fig. 301). While thus the growth 
of some embryos apparently ceases for only 
a very short period, if at all, most seeds in 
ripening lose a considerable part of their 
water and become comparatively dry. Un- 
der such conditions life processes continue 
at a very slow rate, and for practical pur- 
poses the seed is in a condition of rest. 

Fic. 300. Germinating 
seedling of Rhizophora 
projecting from a fruit 
that is still attached to 
a tree. (X 3) 
Many seeds will not 
begin to germinate 
until they have been 
in the state of rest for 
a considerable length 
of time, while others 
will germinate almost 
immediately. 
A period during 
which seeds will not 
germinate is fre- 
quently of great ad- 
vantage, particularly 
when the seeds are 
formed at the end of 
the growing season. 
In many regions the 
year is divided into 
aseason which is fa- 
vorable and another 
which is unfavorable 
to growth. Unfavorable seasons may be due 
to either very cold or very dry weather. It 
is obvious that if seeds began to germinate 
at the beginning of a long cold or long dry season, the seedlings 
would start under very disadvantageous conditions and would 
stand little chance of surviving. In regions where conditions are 




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Fic. 3801. Seedling of 
Rhizophora after drop- 
ping from the tree and 
taking root. (x 3) 
