PLATE 37 
Root of tlie potato in development: 
A. —Radial section through nodal region of underground part of stem, showing origin 
of roots from the pericycle. X 36. 
B. —Transverse section of partly mature root. X 90. 
C. —Transverse section of a young diarch rootlet, showing arrangement of protoxylem 
and protophloem. X 648. # 
D .—Transverse section of fully mature root. X 54 - 
