198 
Structure of Vegetables. 
are called seminal or seed leaves. In some cases the 
seed leaves wither and decay as soon as the other leaves 
begin to unfold ; but in other cases they continue long, 
and remain green and vigorous after the plant has made 
considerable progress ; this may be observed in the 
Yellow Lupine. The cotyledons are abundantly obvi- 
ous in the Garden Bean after it has begun to vegetate, 
and the embryo is seen to push out from between 
them. 
The appendages of many seeds, and the peculiar 
structure of some seed -vessels, are admirably calculat- 
ed to promote their dispersion ; for this purpose seeds 
are furnished with wings, spines, hooks, and scales. 
The downy appendage of many seeds of syngenesious 
plants, as is familiar to every one in the Dandelion, 
wafts them through the air ; the elastic power of the 
seed-pods of other plants, projects their contents to a 
considerable distance; and the barbed structure of 
some seeds retains them in the soil, while the uncoiling; 
of the attached awn forces them deeper. 
Functions of Vegetables . 
When the perfect seeds of a plant are exposed to 
the influence of certain agents, they undergo a very 
remarkable change, in the progress of which plants ex- 
actly similar to those from which they originated are 
produced. 
Germination — The first change which is observed 
in seeds when they are placed in certain circumstances, 
is called germination. Heat, air, and moisture, are ne» 
