EFFECT OF PARASITIC Fl'Mil ON THE CELL-WALL. 



acid the cellulose is dissolved out, and the primary wall remains 

 almost intact, while the secondary after swelling is converted 

 into sugar and gum. Certain fungi (*.//. 7 W/// /<*///* vaporarius, 

 P. Schi'-i init-.ii and P. s////>/////v//x), act in the same manner, 

 first dissolving out and consuming the cellulose before attacking 

 the wood-gum. When woud is destroyed by fungi of this 





K[... Li. 



Kl... 14. 



Kiu. i:{. Trie-held of /'. ! -tr.iyi-d In . lini. The i>ninary 



cell-will is completely dissolved frum in-low upward* <> ", : '>, secondary and 

 tertiary layers .if the w.ilU i-miitini{ in the iindt-r ]i.irtimi of i-.-llnl.i^.- nnlv, in 

 which ^r.iniiles "' chiilk are recn-'nix ililc ; .-, fuiiL,'u-hy|>hae Imrintf through tin- 

 walls, leaving h.'k-N ' ainl . . (Al't.-r K. Marti),,'.) 



KM.. 14. Tr.icln-i'1 "f /'.,.,.. ili-^trnyi-.l liy /' Tin- i rllu'. 



baa been extracted, and the wall consirts only of wood-gum. The Qosurea ire i 



. U i if ilryiiiK-np, but they dn imt i-xtund int<> tlie ].riniary wall c, '. < 

 nf th'- ti-^ur>--. takei l 1 '.' i' tin- IniiiU-n-'l 1'ils .-, and at the l>..iv-lii'U-> .' and < ; 

 riipli- tiiisuri--,. (After It. HartikM 



kind, th<- primary wall, containing but little eellulosr, is hardh 

 aH'ceted, ainl tlie SI-IMMH lury membnnies shrink [> >^r\ her. ^n that 

 numerous tissun-s ;u-e jn-odiired running in a spiral direct iun. 

 eorrespKiiding with that of the .-t nil iliral imi ( l-'i--. 1 .". and 1-1. i 

 The ti-rtiary membram- varies in its natuiv: it may eou-M-t of 



plllr ri'lliilo>i' ill" lie Inure ur le>s Ugnified, Or i'\i-|| ellt icldal 1 



Iii the \vuud-tibres of some plant- < ' '////\//>, limn nlu*. \ tin-. 



