PLATE 53. PINUS MONTICOLA. Tangential section showing the structure of the 

 two forms of medullary rays. X 46.8 



PLATE 54. PINUS GLABRA. (Type of haul pint-s. Sec. 11. 1 Transverse si 

 tion showing the very broad and very dense summer wood, and the structure 

 of a resin canal with very large epithelial cells. >< 46.8 



