﻿Bui. 1131, U. S. Oept. of Agriculture. 



Plate I 



A 



Frost Injury to Thuja plicata, Pseudotsuga taxifolia, and Larix 



occidentalis. 



A .—Transverse section through frost ring in Thuja plicata, showing a pronounced distortion of 

 the medullary rays. (xl35.) B — Transverse section through frost ring in Pseudotsugataxifolia, 

 showing the crumpling of the wood cells that were but slightly u'gnined at the time of freezing. 

 (X135.) C— Transverse section through frost ring in Larix Occident alia sapling (tree .No. 1), at 

 .146 centimeters above the ground, showing an extreme case of lateral displacement of the 

 [medullary rays. (X135.) 



