DISEASES OF TAXODIUM AND LIBOCEDRUS. 



(fig. 1). The shrinkage of the wall causes breaks to ap- 

 pear in the pits (PL 5, fig. 11) and after a time in 

 the walls (e). The shrinkage in a large mass of wood 

 after a time becomes so great that the wood breaks at some 

 point and gives rise to the appearance to be noted in 

 the long hole at the left of the block in Plate 2. The 

 three lamellae of the wood-cell are distinct even in greatly 

 "charred" wood (PI. 4, fig. 2). 



The chemical nature of the wood cells has been entirely 

 changed, and, as has been said, the change from sound 

 wood to completely charred wood is immediate so far as 

 microchemical tests can show. With dilute KOH the dis- 

 eased wood swells to two or three times its size and the 

 breaks in the walls close. A large per cent, is soluble 

 in KOH and from such a solution humus compounds similar 

 to those found in the cypress are obtained. Chlor-iodide 

 of zinc turns the walls brown. When treated with dilute 

 nitric acid the secondary lamellae gradually dissolve and 

 there is left a skeleton framework composed of the primary 

 lamella, the intercellular substance at the angle, and the 

 fine membrane of the pits with the thickened torus. The 

 solution takes place very gradually and can be followed very 

 readily in a thin section. The nitric acid evidently dissolves 

 out the substances into which the secondary lamella has 

 been changed, leaving the more resistant primary lamella 

 intact. From the HNOs solution a heavy flocculent orange 

 mass is precipitated when excess of water is added. This 

 precipitate is very soluble in alcohol and acetic acid, 

 slightly so in ammonia, insoluble in ether, chloroform, ben- 

 zine or acids. When dissolved in absolute alcohol, and 

 cooled, no crystals form, but an oily substance settles on 

 the walls of the dish as the alcohol evaporates. No further 

 attempt was made to determine what this is. Nitric acid 

 and potassium chlorate dissolve the entire wood substance. 

 With EbSO* the walls turn black and swell considerably. 

 Phloroglucin and hydrochloric acid stain the rotted wood 



49 



