DISEASES OF TAXODIUM AND LIBOCEDRUS. 



are yellow-brown at the edges, transparent and soluble in 

 5% KOH in the form of the acid or as ulmate or humate; 

 humin and ulmin simply swell in 5% KOH. "In the 

 humification yellow-brown places appear on the cell mem- 

 brane, which can be bleached out with KOH, in the form of 

 ulmin or humate ; the remaining cell membrane shows dis- 

 tinct cellulose reaction. Lignified membranes ulruify with 

 difficulty, although wood cells can change completely into 

 peat." Griesebach (1. c.) mentions the transformation of 

 wood of Erica Tetralix and Calluna vulgaris into ulmin 

 substances. Humic acids have been found in plants, and 

 Friih mentions a number of cases. Thus according to 

 Lucas, Einhof extracted the same from spores of Agaricus 

 atramentarius , while he himself obtained one from Uredo 

 segetum. Friih isolated humic acid from spores of Ela- 

 phomyces granulatus. 



In the wood of Taxodium in which the large masses of 

 humus compound were found the transition from lignin to 

 the humus bodies was very evident. PL 3, fig. 2, 

 represents a section made through the border of a hole, 

 after staining with phloroglucin and HC1. At " g " the 

 primary lamella is seen, dark red, indicating the presence 

 of coniferin, etc. In the next row of cells the interior is 

 coated with yellow-brown masses (h) which in the un- 

 stained wood contrast beautifully with the almost white cell- 

 wall. These masses are found to be humus substance, 

 readily dissolved by dilute KOH. The phloroglucin stains 

 the secondary lamella. Between this normally lignified 

 portion and the inner humus layer is a layer staining yellow. 

 This is evidently similar to the membrane already described 

 (PI. 3, fig. 1 d "), i. e. the wood substance gives neither 

 a lignin nor a cellulose reaction. After treatment with 

 KOH it stains deep blue. This is in part the process as 

 described by Friih, except that here there is an intervening 

 step between the lignin and the humus substance. Pass- 

 ing now from the cells just described, one finds the layer 



17 



