PLATE 32 
Types of elements of the potato: 
A. —Radial section of outer cortex, collenchyma, subepidermal layer, and epi- 
mens with stomata. X109. 
B. —Tangential section of part of vascular cylinder of partly mature stolon showing 
numerous sieve tubes and two porous vessels. X218. 
C. —Tangential section of young stem showing sieve tubes of internal phloem and 
protoxylem. X109. 
D. —Tangential section of partly mature stem showing cambium and medullary 
ray initials. X104. 
