LIFE-HISTORY OF THE HERB ROBERT 97 
from the root to the leaves for the purposes of food 
manufacture. There are four bundles of them in 
each leaf stalk or “ petiole,’ one being much smaller 
than the other three; we can see this much for 
ourselves with a little trouble, if we remember how we 
manipulated the Iris root, and the illustration shows 
a section of a petiole that has been divided into two 
crossways ; so that we are again looking as it were into 
the pipes which have been cut across. 
The starch grains that are formed and which 
help to nourish the plant and to provide what is 
necessary for its growth and other activities are 
extremely small, their diameter being not more than 
359 Of an inch as a rule, and often very much less: 
they, however, respond readily to the iodine test, and 
if we squeeze some of the juice from the petiole on to 
a glass slide we can in this way easily satisfy ourselves 
as to their presence there. 
Now, if we watch one of the young plants in the 
open we Shall find much to interest us in its growth, 
although of course we cannot witness that cell division 
of which I spoke previously ; but we shall see this: 
that for weeks or months it forms nothing but leaves, 
at any rate above ground—tt is in fact growing up. 
If we watch a single leaf from the time that the 
unexpanded blade begins to appear, we shall find that 
it goes on increasing in size until it has reached its 
maximum. The largest one that I found measured 
five inches by four and three-quarters, but this was 
exceptionally big. Later on the leaf begins to wither 
and to lose its green colour : it may turn a brownish- 
yellow or more or less red, and sooner or later it dies 
and decays. Its stalk withers too, until there is 
nothing left of it but-a thick ruddy stump. 
