State Museum of Natural IfisTonv. ^9 



applanatus,¥i\; P. versicolor, Fr.; P. pergamenut<,Fr.; D(edalea unicolor, 

 Fr. ; D. quercma, Pers., and Lenzitea vialk, Pk. 



PolyjMrus ajyjyianatus attacks the heart wood of the white oak tie 

 and is very destructive, and requires a moderate amount of air and 

 moisture for its growth. The characteristic decay of these ties is 

 from the under to the upper side, and is most rajjid in stone ballast, 

 or a coarse ballast which retains a little moisture and permits access 

 of air. In a ballast containing considerable loam, which checks the 

 cu'culation of air, and in wet cuts, the growth of the mycelium is 

 retarded and the durability of the ties increased. In i^orous ballast, 

 unless wet, the deeper the white oak ties are imbedded the better are 

 the conditions of the growth of the fungi and the more rapid the 

 decay of the ties. On the contrary, only imbedding the ties sufficient 

 for the stability of the track increases the service of the ties by 

 retarding the rapidity of the upward growth of the mycelium. 



Polyporus versicolor attacks the sap wood of white oak ties and 

 posts, and to a limited extent the heart wood. 



Polyporus pergamenus attacks those ties from which the bark has not 

 been removed. 



Dcedalea unicolor, D. quercina and Lenzites vialis have been found on 

 ties laid on railroad bridges. 



The structure of the white oak is so firm and dense that .it readily 

 sustains the heaviest traffic and it is quite difficult to impregnate the 

 internal cells of the ties. Unless a process has been used which would 

 sterilize the spores lodged in the wood or possible traces of mycelium, 

 the exterior treatment on the unseasoned wood prevents the escape 

 of the internal moisture, the same as a coat of j)aiut. This will hasten 

 decay, for it furnishes the requisite conditions for fermentations and 

 internal growth of mycelium. 



The fungi attacking ties of the chestnut, Casfanea vulgaris, variety 

 Americana, A. D. C. {Castanea vesca, L., variety Americana, Mx.), are 

 Polyporus sulphureus, Fr.; P. spumeus, Fr. ? ; P. hirsutus, Fr.; /'. versi- 

 color, Fr.; P. pergamenus, Fr.; Agaric us Amei-icanus, Pk. and A. sub- 

 later if ius, Schooff. 



Polyporus sulphureus is also very destructive to tclegru]>li p<ilt>s miuI 

 large posts, attacking them near the ground line. 



The chestnut contains naturally a stronger antiseptic tluiu tlii; 

 white oak and resists, in contact with the soil, the growth of the 

 fungi until the antiseptic is destroyed by the air, or contact with 

 the rails and spikes. The decay of the chestnut tie is from the 

 top downwards; therefore the deeper the tie is imbedded 

 the longer the body lasts. The full advantage of this is lost in 

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