5/8 



By surveying the cross-section as a whole, which may serve as an ex- 

 ample of frost discoloration for all trees, we see that the region of the bud 

 cushion is the most susceptible part of the branch. In this region the twig 



Fig. 128. Browning- and splitting ot the tissue of a pear branch produced by 



artificial frost. 



has the slenderest wood ring and the largest accumulation of parenchyma. 

 The spots kept dark in the drawing represent the browned parts. So far 

 as susceptibility is concerned, the ])ith crown and the medullary rays follow 



