34 RKACTION OF HOST TO PARASITIC ATTACK. 



Accuiiiulatioii of starch is described by R Hartig ^ in spruce- 

 needles attacked by Zophodermium macrosporum. In the pre- 

 sence of the fungus-mycelium, an increased production and 

 storage of starch takes place at a time when it is being only 

 slowly formed in normal needles. If the needles become diseased 

 during May, a season when they are already full of starch, 

 this remains intact in the dead cells till Octoljer, wlien it begins 

 to be used up. 



Wakker ol)served accumulation of starch in cumfiey with 

 Accidium aspcrifolii, in buckthorn with Accidium rhamni, in 

 hawthorn with Roestclia laccrata, in Sispnhrium officinale and 

 other plants with Cystopus, in roots of Brassica inhabited by 

 Plasmodiophora brassicae, and in hypertrophied scales of alder 

 catkins with Exoascus. Many other examples are gi\-eu through- 

 out the literature of plant-pathology. 



Particularly noteworthy is a case of starch preservation in 

 ■oak-wood destroyed by Polyporus dryadeus and P. igniarius 

 simultaneously.'^ In the wood infested by 

 either of the fungi alone the starch is dis- 

 solved, but at the l)oundary where the two 

 meet it remains in the medullary rays ; 

 these, in consequence, appear snowy white, 

 i| ; 1 and consist almost exclusively of unchanged 



^ <, starch-grains, while the lignified cell- walls 



S ! 'I have been converted into cellulose or coni- 



I; j-^ pletely absorbed (Fig. 10). Loew^ remarks in 



\-:. regard to this: "One must assume here a 



'|; j ;,) variation in the kinds of diastase, and a 



' 7 '1; ;' ..' neutralizing effect of the one on the other, 



in somewhat the same manner as pepsin acts 

 on ty rosin. One is also reminded of two 

 optical antipodes which easily unite into an 

 i.f'^ak-wwd 'destroyed 'by Optically ucutral body " {e.g. sugar isomers). 

 stiif^fuir'''of^undfssoived The dissolutiou of starch by fungi has 

 (v"T,'^eu7;ro?r'"'''" Ijeen examined in detail by Hartig. The 

 wood-destroying fungi dissolve the reserve 

 starch-grains laid up in the wood-parenchyma in various ways. 

 Assuming the view of Naegeli, that starcli-grains consist of a 



1 Wichtiije. Kranhheiten d. Waldhdumcn, 1874. 



2R. Hartig, Zersetzungtierscheimmijen, 1878. 



='Loew, 0., Ein naturliches System d. Gift- Wirkiiuffen. ]Miiiiieh, 189.'}. 



