von Schrenk — Trees of St. Louis as Influenced by Tornado. 41 



EXPLANATION OF ILLUSTRATIONS. 

 Plates III.-IX. 



Plate III.— Platanus occidentalis. Above, transection of twig two years 

 old, X 65. Below, transection of twig injured by the storm, X 75. Both 

 from photomicrographs, a, Wood-ring formed in 1895. 6, Wood-ring 

 formed during April and May, 1896. c, Wood-ring formed after May, 

 1896. 



Plate IV.— Acer dasycarpum. Above, transection of twig two years old. 

 Below, transection of twig injured by the storm. Both from photomicro- 

 graphs, X 75. a, Wood formed during April and May, 1896. 6, Wood 

 formed after May, 1896. 



Plate V.— Platanus occidentalis. Transection of wood, a, Wood formed 

 after May, 1896. 6, Wood formed during April and May, 1896. /, Fall 

 wood, 1894. *, Spring wood, 1895. 



Plate VI. — Acer dasycarpum. Transections of wood. 1, Fall wood fol- 

 lowed by spring wood. 2, 6, Wood cells formed in April, 1896, and com- 

 pressed by the wood outside of it. /, Wood formed in the fall of 1895. 

 o, Large-lumened cells formed after May 27, 1896. r, Break in the tissue. 



PI. VII.— Salix nigra. Transections of wood. 1, Healthy wood. /, Fall 

 wood, s, Spring wood. 2, Oedematous wood. I, Division of large vessel. 



PI. VIII.— Trees showing effects of bark scorching. 1, Bobinia Pseud- 

 acacia. 2, 4, 6, Acer dasycarpum. 5, Ulmus Americana. 



PL IX. — 1, Transection of linden trunk (Tilia Americana) showing drying 

 effects of bark scorching. 2, Transection of maple trunk {Acer dasycar- 

 pum) , showing effects of bark scorching. In the wood between the dark 

 lines numerous fungus hyphae occur. 



Issued January 29, 1898. 



