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



EXPLANATION OF ILLUSTRATIONS. 

 Plates III.-IX. 



Plate lll.^ Platanvs 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. b, Wood-ring 

 formed during April and May, 1896. e, 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. b, 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, b, 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.— Saliz 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, i, 6, Acer dasycarpum. 5, Ulmus Americana. 



PI. 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. 



