UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 869 
Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 
Washington, D. C. 
PROFESSIONAL PAPER 
September 30, 1920 
THE INHERITANCE OF THE LENGTH 
OF INTERNODE IN THE RACHIS 
OF THE BARLEY SPIKE 
By 
H. K. HAYES, Head of Section of Plant Breeding, Division of 
Agronomy and Farm Management, College of Agriculture, Uni- 
versity of Minnesota, and HARRY V. HARLAN, Agronomist in 
Charge of Barley Investigations, Office of Cereal Investigations 
CONTENTS 
* 
Scope of the Experiments 
Historical Review 
Pure-Line Varieties Used in These 
Studies 
Reliability of Experimental Methods . . 
Effects of Environment and Varying 
Sources of Seed on Density .... 
Page 
Purity of Parental Forms ...... 5 
Inheritance of Length of Internodes in 
Crosses between Pure Lines .... 9 
Summary of Results 20 
Discussion of Results 21 
Conclusions 24 
Literature Cited 25 
WASHINGTON 
GOVERNMENT PRINTING OFFICE 
1920 
