EFFECT OF PARASITIC FUX(4I ON CELL-CONTENTS. 35 



cellulose and a granulose part, Hartig describes the process thus 

 (Fig, 11). The mycelium of species like Polyimms igniariuti 

 gives off some ferment which dissolves the starch-grains, by cor- 

 roding them from the outside inwards, so as to form holes and 

 canals similar to those in 

 starch-grains in process of 

 dissolution in the cells of a 

 sprouting potato. In others, 

 r.(j. TJielephora j^crdii:, the 

 granulose is first dissolved 

 from without inwards, so that 

 finally only the starch-cellulose 

 remains, occupying a region ^^^ u.-starch grains f.-om the oak, in pro- 



t-.iwflvrlq f-liP ontpr i^nrfcj nf cess of dissolution by ferments, o, of r/,«/tyW.om 



lOWaiQS tne OUiei parts OI ,,erdix\ b, ot Polnporm sulphureas; ,;, ui P„ly 



rl-iP trrnin <i<5 o Irinrl nf ViiksV porm igniarhu. In a and 6 the iodine-reaction 



me giain as a kmCl OI nUSk, Ig shown by shading. (After R. Hartig.) 



which is in time gradually 



used up. In Puhfporus sulphiircus the operation is reversed ; 

 the starch-cellulose appears to be dissolved' out first, leaving 

 a residue of granulose. These observations were based on 

 the assumption that the starch-grain consisted of a granu- 

 luse portion which turned blue with iodine, and a starch- 

 cellulose portion which became yellow ; or again, on treating 

 the starch-grains with dilute acids the granulose was dissolved, 

 while the cellulose remained in the form of a skeleton. 

 Although more recent investigations have shown that the 

 cellulose-skeleton results from the action of the acids, and that 

 this view of the constitution of the starch- grain was not quite 

 c(jrrect, yet Hartig's observations prove that the various fungus- 

 ferments have each their own action on starch-grains : his 

 results are also supported by other facts. 



Other fungi besides Polyporeae utilize the starch of their 

 host-plants, thus PhijtoiMhora in leaves of the potato. 



The formation of calcium oxalate is influenced by action of 

 [tarasites. From Wakker's synopsis of the phenomena of hyper- 

 trophy, we find that calcium oxalate normally present in crystal- 

 sacs in leaves and flowers of Rhamnvs Frangula, is wanting in 

 parts deformed by Aecidiam rhamni ; crystal-sacs are less 

 abundant in diseased stems than in healthy ; the calcium oxalate 

 in galls of E>oha.sidinm is not present in crystal-sacs, as in the 

 non-deformed organs, but as ill-defined solitary crystals of limited 



