Plate V11I. 



FIG. 20. Transection of a bicollateral flbro-vascular bundle from tlie stem of 

 Cucurhita Pepo. A, Parenchyma cells of tlie fundamental system surrounding the 

 bundle; B, B, larjre thick-walled vessels of the xylem; .,', t', sieve-tubes of the 

 phloem; D, I), thin-walled cells of the cambium. (xL>0.) 



