BULLETIN OF THE 
No. 183 
Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Ch 
April 13, 1915. 
(PROFESSIONAL PAPER.) 
MORPHOLOGY OF THE BARLEY GRAIN WITH REFERENCE 
TO ITS ENZYM-SECRETING AREAS. 
By Albert Mann, Plant Morphologist , Office of Agricultural Technology, and II. V. 
Harlan, Agronomist in Charge of Barley Investigations, Of ice of Cereal Investiga- 
tions. 
CONTENTS. 
Page. 
Introduction 1 
Structure of the barley grain 2 
Development of the barley grain 5 
Germination 8 
Conversion of the endosperm.. 9 
Rfeume' of the conclusions of other investi- 
gators 10 
Source of diastatic ferments 12 
Locat ion of diustase secretion 17 
Page. 
Source of cytatic and proteolytic ferments. . . 18 
Function of the aleurone layer 18 
Greater diastatic power of small-berried and 
of h igh-nitrogen bar ley s 19 
Efficiency of conversion 21 
American barleys 27 
Modifications possible by culture 28 
Foreign barleys 30 
Summary 31 
INTRODUCTION. 
The value of the barley crop to the American farmer depends upon 
two factors, the yield per acre and the price per bushel. An Increase 
of revenue is as readily effected by one as by the other. The yiel I is 
necessarily an agricultural problem; the price is also, within certain 
limits. Although the daily price of any market product ordinarily 
varies over a considerable range, higher values are placed upon those 
offerings which most perfectly meet the requirements of consumers. 
A superior quality is the equivalent of a greater quantity. The nea rer 
a farmer can come to producing a product ideally suited to its uses, 
the higher will be the price which he will be able to command. 
By far the greatest demand upon the barley crop is for the purpose 
of malting. This operation consists essentially in the breaking down 
of the cell walls of the endosperm of the barley grain so as to leave its 
starch grains exposed to later enzymatic actions, and also in the 
abundant production of these enzyms, both the diastatic and pro- 
teolytic. The abundant formation of diastase has long been con- 
Xote.— This paper is intended for distribution to agronomists, station directors, brewery chemists, and 
selected maltsters. 
75719°— Bull. 183—15 1 
