DISEASES OF TAXODIUM AND LIBOCEDRUS. 39 
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 ulmify 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 
Frih 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. Frith 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 HCl. 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 
(Pl. 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 Frih, 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 
