A GRAIN OF BARLEY. 109 
a symogen, that is a potential ferment which is only brought 
into full activity by the presence of a small quantity of acid. 
The acid requisite for this quickening into activity of the 
ferment is derived under natural circumstances from the 
growing embryo. The complex nitrogenous contents of the 
endosperm cells are broken down to J/eucin, tyrosin, and 
perhaps asfaragin, and can in this form readily permeate 
from cell to cell until they finally reach the growing embryo 
and contribute to the development of the young plantlet. 
Besides the disappearance of the starch and proteids of 
the germinating grain, as they are gradually laid under con- 
tribution by the growing embryo, we note that even the walls 
of the starch-containing cells themselves are attacked and 
ultimately disappear. Whether this solution of ce//ulose is 
brought about by the action of diastase, or of a special 
ferment, is not at all clear at present. The solution of 
cellulose under these circumstances is, however, not by any 
means an isolated case. In some seeds, such as the date, 
for instance, the reserve-material of the endosperm consists 
entirely of cellulose, which is slowly dissolved and absorbed 
by the young plant as it grows. 
The case of the fruit of the Ivory Palm (Phytelephas 
“macrocarpa) is even more remarkable. The endosperm of 
this nut consists of a mass of cellulose so extremely hard that 
it is known as ‘vegetable ivory,” yet the whole of this is 
absorbed during germination, and serves as the first nourish- 
ment of the embryo. 
I have now very briefly sketched some of the chief physio- 
logical processes involved in the germination of our little 
barley grain, but many of them are still very obscure, and 
require long and patient research to thoroughly elucidate 
them. The work that is being done in other Orders of 
plants is throwing a great deal of side light upon them, but 
with our present knowledge of the minute anatomy of the 
grain, which is far in advance of the physiology, we are, I 
think, in a fairly good position to attack these problems from 
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