University of California Publications in Agrkultukal Scienciks 



Voliimo 2, No. 1.'), pp. 401-432, plates .IS-Gl, 1 fifjurc in text 



Issued May 8, 192!) 



University of California Press 

 Berkeley, Cvlifornia 



CAiiBRiDGE University Press 

 London, England 



