22 BULLETIN 183, U. S. DEPARTMENT OF AGRICULTURE. 
malting. The perfection with which an endosperm undergoes diges- 
tion depends upon the amount of diastase present and upon the 
location of the endosperm with reference to the diastatic source. 
It is the aim of malting to carry the disintegration of the en- 
dosperm only to that point where cytatic action has-been com- 
pleted and where diastase formation has reached a large total which 
has been distributed through the grain. Very little starch conversion 
is desired in the process of malting. Indeed, none is desired, since 
the sugars thus produced are in part absorbed by the growing plant 
and not only lost but changed into undesirable products. The low 
temperatures at which the grain is malted are for the purpose of 
restraining this con- 
version. Every- effort 
is made to prevent 
the absorption by the 
plant let of the con- 
tents of the proximal 
region of the endo- 
sperm before the 
enzymatic, secretions 
have reached its dis- 
tal end and have per- 
meated the dense 
starch areas in the 
upper flanks of the 
grain. When this is 
attained the embryo 
is killed to prevent 
any further absorp- 
tion. The object of 
malting is, therefore, 
Fig. 4.— Two grains of aBohemian barley; a broadly oval-shaped grain to subject all parts 
well adapted to malting with little loss. Q f ^ e endosperm to 
the initial effects of enzyms with as little loss as possible. The ideal 
condition would be a simultaneous attack upon every cell wall and 
every grain of starch. This is impossible with the source of the 
action localized at one extremity of the grain. However, the coordi- 
nation of the scutellum with the endosperm has a marked effect. 
The shape of the gram with reference to the size and shape of the 
associated embryo has in more than one variety been the deciding 
factor between a good and a poor malting barley. If the great mass 
of the starch be near the embryo, as in the short, thick grain shown 
in figure 4, the disintegration of the endosperm is readily and uni- 
formly accomplished, but if it be distant, as in long, slender grains, 
the complete modification of the endosperm mass can not be accom- 
