MORPlTOLOfiY OF THE BARLEY GRAIN. 
5 
DEVELOPMENT OF THE BARLEY GRAIN. 
An understanding of the office and behavior of the various organs 
of the barley grain is greatly facilitated by observations upon their 
origin and development. Some of these organs are functional 
throughout the existence of the seed; others important in the early 
Stages afterwards disappear, while still others become so modified 
as to be serviceable in a totally different way. 
The flower of the barley plant is inclosed within the flowering 
glumes, as in all grasses. It consists of a simple ovary containing a 
single ovule. The stigma is two branched and plumose. Three 
versatile anthers attached below the ovary fit into as many natural 
angles in the glumes. On the dorsal side of the ovary are two 
lodicules. 
At the time of flowering, the ovary wall is a but slightly modified 
vegetative structure. It consists of the usual epidermis, a colorless 
parenchyma of several layers, a chlorophyll-bearing parenchyma, and 
an inner epidermis. The chlorophyll layer is the only one in any 
way exceptional. The cells of this lie with their long axes at right 
angles to that of the others and tangential to the grain. Inside the 
ovary are two integuments which probably act as conductive tis- 
sues to the growing pollen tube during fertilization. Each is formed 
of two layers of thin- walled cells. The cells of the outer integument 
are somewhat larger than those of the inner one and are much thin- 
ner walled. The contrast between the two integuments is very 
evident in Plate I. Inclosed by the two integuments is the nucellus, 
which is in turn surrounded by its own investing membrane, con- 
sisting of a single layer of cells. In the parenchyma mass of the 
nucellus is the embryo sac, which before fertilization contains the 
usual right cells. At this stage of development the cells of all the 
tissues are filled with plasma. 
After fertilization the ovary increases in length and width. As 
the essential parts of the developing seed are taking shape, certain 
now useless portions of the enveloping structures become modified 
and in some cases absorbed. The plasma gradually disappears from 
the cells of the outer integument, the cell walls become transparent, 
and finally dissolve and disappear. The inner epidermis is also 
absorbed, although not always completely, as traces sometimes per- 
sist at maturity. A little later, portions of the ovary wall begin to 
weaken. The starting point is usually just outside the chlorophyll 
layer, and the process advances outward through the overlying 
parenchyma layers. At maturity this tissue is represented by a 
compressed mass of almost disconnected cells. In the earlier stages 
of growth it is this reduction of tissue that establishes the "green 
ripeness'' of Kudelka, the removal of the overlying cells bringing 
the chlorophyll layer nearer to the surface, thus intensifying the 
