Osborne^ on th^ Wheat Plant. 
109 
wliole structure of the root ; this^ by the process of colouring , 
which I shall presently describe^ I now can easily prove to be 
the case. It is highly transparent and is seen as a clear glass- 
like envelope to the substance it invests ; I will call it " epi- 
dermic plasm I believe it to be identical with the connecting 
membrane or plasm by which the cells of the capsules are 
held in position. If the point of a growing root is removed 
from the plants and the capsule separated on to a slide of 
glass, a drop of fluid added, and then some compression made 
with a thin glass cover, by a patient manipulation of the 
illuminating portions of the microscope, this plasm is very 
easily made out. 
Having dealt with the general features of the growth of 
the root, I will now turn to that of the plumule or leaf. A 
section made with care through the white substance, from 
which the plumule and roots both protrude, gives a beau.tiful 
view of the early formation of the former. Several layers of 
an oval-headed cell- structure are seen, the one longer than 
the other, i. e., more advanced in growth, the shortest or 
youngest being very small. When detached from each other 
their outline is that of a blunt spearhead (PL V, fig. 19) ; 
at this stage their substance consists of a cellular texture,' of 
which the cells are very small as to their actual area, with rather 
thick walls of plasm. Towards their base, in the centre of each, 
is the well-defined indication of an upward line of spiral fibre. 
These are the embryo leaves. They have the same epidermic 
plasm as the roots, and into it are seen to project small 
points, the future hairs on the leaf of the plant. They have 
capsules, so far as I can make out, identical in structure 
with those of the root, although adhering more closely to the 
substance covered, and the component cells do not separate 
in the way they do in that part of the plant. 
As these young leaves prepare to enter into the outer world 
they fold themselves longitudinally into a very small compass 
(PI. V, fig. 29), and carry on with them, until they have ob- 
tained an inch or so of growth, a straw-coloured cellular en- 
velope of stout texture (PI. V, fig. 30) ; this appears intended 
to protect them as they force their way through the soil and on 
their first exposure to the weather in the outer world. It has 
occasioned me some surprise to find the chlorophyll or green 
colouring matter existing in leaves at so early a stage of growth, 
that I can hardly attribute its existence to any action of light. 
The spiral and other fibre given ofi* into the leaves origi- 
nates from a mass of the pitted or dotted cell-tissue which is 
seen in the centre of the white substance, from which, as I 
have stated, plumule and roots both grow. If a section is 
