The Seed and its Germination. 
501 
narrow ends resting on the cells of the scutellum. They have 
a length of about -^-^ to inch. The endosperm is pressed 
closely upon this layer of cells, and consists of a mass of cells 
with thin walls, their interior being packed full of starch grains 
(fig. 8). Examination of the germinating barley seed by the aid 
of the microscope shows that the first process that takes place is 
the swelling up and dissolving of the walls of the cells of the 
endosperm in which the starch is contained. This solution 
begins always immediately under the cells covering the scutellum, 
and extends gradually throughout the endosperm. The struc- 
ture thus becomes friable or mealy, owing to the starch grains 
being set free from the constraint of the cell walls. A little 
later the starch grains are attacked — again immediately under 
the scutellum. The 
grains become pitted /77\ /7\ /pA 
on their surfaces, and ( ^7 jfty U^j Vf7 
the pittings increase 
cn-aduallv and become Fi °- ^ --integration of Wheat Starch 
*2 .1.1 by Diastase. 
deeper, SO _ that the fl , >5 c, d, e represent successive stages. 
grains are irregularly 
broken up (fig. 17). The disintegrated starch grain then be- 
comes dissolved, the starch being converted into something 
soluble in water, which we shall see later is a form of sugar. 
Both these processes have now been ascertained to be due 
to the action of unorganised ferments. The one which causes 
the disruption of the starch has long been known under the 
name of diastase. The second has only recently been discovered 
by Messrs. Brown and Morris. These investigators have shown 
that both the ferments take their origin in the layer of cells 
which have been described as coating the scutellum, and which 
they consequently have called a secretory epithelium (fig. 16, a). 
The starch and cellulose so disappearing are found to be 
replaced by certain forms of sugar, and the process is no doubt 
one of conversion of the former into the latter, just as is the 
case in the digestion of starch by an animal. This can indeed 
be proved by preparing a solution of the ferment from the 
germinating barley and acting with it on a quantity of starch 
in a test-tube. To carry out this experiment it is necessary to 
dissect out the embryos from a number of germinating grains, 
and grind them up with a little water containing a trace of 
chloroform, the latter being used to prevent the growth of 
micro-organisms or bacteria in the solution. The mixture 
must then be allowed to stand for a day, when it can be filtered. 
There results a clear liquid which contains the ferment or dia- 
stase. On mixing this with a certain quantity of thin starch 
