The Plant 
37 
that taken in from the atmosphere, and in the coloured 
cells of the leaves the great changes are made. 
We will again review those substances taken in by the 
plant from the soil and from the air, and try to trace them 
into the substance of the plant itself. 
First, the plant takes up from the soil — by means of 
its root hairs — nitrogen, oxygen, hydrogen, phosphorus, 
potassium, sulphur, cal- 
cium, iron, magnesium, 
1 silicon, and chlorine; 
I while from the air — by 
i means of the stomata in 
the leaves — carbon is 
i taken. These substances 
i unite in the chlorophyll 
I of the leaves under the 
j action of sunlight. Great 
j changes then take place. 
| The brighter the sun- 
1 shine — as a general rule 
— the quicker the change goes on, and consequently the 
1 quicker the growth of the plant. 
The first substance we know to be found is starch. 
This consists of 6 parts of carbon, io of hydrogen, and 
j 5 of oxygen — C 6 H 10 O 5 . Another that is formed later 
i is grape sugar. This also consists of carbon, hydrogen, 
i and oxygen — 6 parts of carbon, 12 of hydrogen, and 
: 6 of oxygen (C 6 Hi 2 0 6 ). Again, we have cane sugar 
I (C ]2 H 22 O n ). Then we get cellulose, which is the material 
of the cell wall, and is C 6 H 10 O 5 . We therefore see that 
this is of the same formation as starch. The living sub- 
Vertical Section through Leaf, showing Epi- 
dermal, Palisade, and Spongy Tissue, and 
Stomata cut through 
