290 MINNESOTA BOTANICAL STUDIES. 



60, 61. Sections through the transition-region of a young seedling 



(x 60). 



PLATE 43. 



62. Cross section of a secondary root (x 62). 



63. Cross section of a primary root in which the traces of the third 

 and fourth leaves continued distinct through the transition-region, and 

 at the point of this section, formed a tetrarch arrangement with the 

 two cotyledon-traces (x 57)- 



64. Cross section of a primary root in the lower portion of the 

 transition-region (x 25). A central mass of pith is completely sur- 

 rounded by metaxylem. 



65. Longitudinal section through the tip of a secondary root 

 ( x no). A flake of tissue, torn from the primary root, adhered to 

 the tip of the secondary root and appears in the section. 



