GUM—MUCILAGES. 165 
morphosis of the membranes in the medulla and medullary rays 
(Fig. 79). 
In the Amygdalex, however, gum also occurs abundantly in 
the vessels and other elements of the wood, and often even en- 
ee 
} 
Fic. 78.—The formation of gum in cherry-wood; g, aggregates of gum formed through 
metamorphsis of the cell-membranes; r, vessels more or less filled with gum; m, medul- 
ary rays; jf, annual ring, spring wood; jh, annual ring, autumn wood (Tschirch). 
tire groups of cells of the woody structure suffer a conversion 
into gum (Fig. 78 g), as in the so-called gum discase. 
