1895 



THE MICROSCOPE 



135 



served crossing at various angles the medullary rays. 

 The cork in both is colored a deep x^^^^pl^^ '^^^ ^^^^^ col- 

 oring matter is bleached out only with difficulty, even 

 by Labarraque's solution. This coloring matter appears 

 to differ in composition from the reddish-brown color- 



$ 



Fig. 2. 



ing matter found in the tissues betw^een the bands of 

 cork, for not only is the color a different shade of red, 

 but it bleaches more readily. Tests for tannin show that 

 in both species, also, the white or colorless younger por- 

 tions of the bark contain little of it, while the older por- 

 tions, particularly the dead sieve and parenchyma tis- 

 sues between the bands of secondary cork, are exceed- 

 ingly rich in it. Stone cells of large size and often quite 

 irregular shape occur, either isolated or clustered in 

 groups of several or many, throughout all except the 



