98 LIFE OF A TREE. 
of oxygen gas from the air.* This, of course, we 
cannot perceive by our senses; but it is a well 
known fact, and is the source of the warmth felt. 
In so doing, a most singular thing takes place,— 
the starch becomes converted into sugar, and thus, 
as sugar is easily dissolved in water, while starch 
scarcely dissolves in cold water at all, the young 
plant receives its first nourishment in a liquid 
form. Thus we see that the sweet taste of malt 
is accounted for. 
We said that the sticky substance remaining 
after washing “dough” in water is gluten. It 
may now be asked, What becomes of this ingre- 
dient of the seed when the latter begins to 
germinate? This question has puzzled some 
of the most eminent chemists; and although we 
believe we now know what takes place more 
perfectly than formerly, yet we must not deny 
that it is still very obscure. It seems to be 
converted into a new substance, so that, instead 
of remaining insoluble in water, it is now quite 
soluble, and therefore is just in that condition 
* The composition of the air is as follows. Nitrogen and oxygen, 
with small but vastly important traces of carbonic acid gas and 
ammonia. 
