a Morton's Cyclopedia of Agriculture, 1856, vol. ii. p. 1116. 



b H. Dorph-Petersen, Director, Danish Seed Control Station. See Lands- 

 mandsblade. No. 47, 1906 ; also Mitt, der Deut. Land. Gesell., December 12, 

 1906, p. 474. 



c Maier-Bode, Die Bekampfung der Acker- Unkrauter, 1908. 



d Dr. Fr. Nobbe, Handbuch der Samenkunde^ 1876. 



e E. Korsmo, Kampe.n mod Ugrasset^ 1906. 



/ P. Sorauer, Pflanzenkrankheiten. 



