4 NEW ZEALAND NATURE-STUDY BOOK 
and pouring off the clear liquid which remains. Empty 
a small quantity of the clear starch-solution into a test 
tube containing water and add a few drops of weak 
iodine solution—in which a small quantity of potassium 
iodide has been dissolved. The liquid will immediately 
turn blue owing to the formation of iodide of starch. Any 
portion of the plant, therefore, giving this characteristic 
blue colour on being treated with iodine solution, we may 
reasonably conclude contains starch. 
The best way to prepare such a solution is to dissolve 
a few crystals of potassium iodide in a little water, and 
then add a small quantity of iodine until the solution is 
a pale amber colour. 
Germination and early stages of growth of 
the Bean Seed.—In order to observe the process of 
germination and stages of 
growth, place some seeds of 
the Broad-bean in damp saw- 
dust. A good number of 
seeds should be planted, and 
after the first thirty-six hours 
a few of these should be taken 
up every day or two and 
examined, 
Fig. 3.—A, Germination of Broad : 
Bean, showing radicle, 1’, just emer- Under the influence of heat 
ging. B, later stage, showing and moisture the seed swells 
plumule, pl, beginning to with- 
draw itself from seed. up, and the radicle or young 
root breaks through the 
seed-coat at the micropyle. The radicle immediately 
begins to grow downwards (under the action of gravity) 
and, as it becomes larger and thicker, the seed-coat 
gradually opens exposing more and more of the cotyledons. 
In a short time a swelling appears at the upper end of 
the radicle, and the plumule, or young stem, forcing 
itself out of the seed, at once begins to grow upwards. 
