State Mlsecm of Natural History. 87 



habitats and growth of defiiiito sjjecies of fungi is requiied to bent 

 adapt the means to accomiDlish the desired work. Now that knowl- 

 edge of the habitats of species of fungi has been acquired, simple 

 and effectiA'e preventive measures suitable for many cases, without 

 treatment, can at once be put into practice. 



The study of the decay of timber used for construction is rendered 

 very difficult in most cases, from tlie fact that the entire structure of 

 the wood may be destroyed by the gi'owth of the mycelium, or its 

 fermentative process, of the fungus without fructification taking place. 

 This is especially true of railroad ties and bridge timbers. So little 

 is seen iu proportion to the destruction accomplished, it is due to this 

 feature more than to any other, that the true function of the fungi on 

 wood is not more generally understood by users and consumers of 

 timber. It is not strange the idea is so prevalent that fungi are the 

 accompaniments, instead of the cause of the decay of wood. A 

 growth of mycelium, nearly similar to that shown in Fig. II, * of a 

 fungus on the under side of a plank, as in station platforms or 

 between boards when piled in close contact, has not been sufficient 

 in most cases to call attention to the injury, if not the desti'uctiou of 

 the plank or timber uj^on which it is growing. 



Fig. II shows the mycelium of Polyporus radula, Fr. growing on 

 the under side of a jjlank from a station i:)latform. After the myce- 

 lium has run over the wood in a dense mass, then, by means of the 

 fluids it generates — some of them having an acid reaction — the fibers 

 or wood cells are softened and penetrated by the mycelium, and in 

 this way the process of disorganization is carried on. 



This causes the wood to shrink, crack, and finally fall to pieces. 



The mycelium of many other species of the higher Fungi differs 

 from this to some extent, but the final effect of its growth on and 

 through the wood is to destroy it. Besides the visible mycelium there 

 are many other growths and ferments, invisible to the eye, which 

 cause a ra^Did internal decay of large unseasoned painted blocks, such 

 as truck bolsters, transoms, buffers, dock timbers, and end sills to cars. 



In warm and damp weather it is not uncommon for such growths to 

 occur upon timber when piled in close contact, according to the species 

 of wood and fungi, in three to eight weeks. In this viciuit\ the tim- 

 ber on which such growths have started may not be considered suf- 

 ficiently injured for construction — to be rejected. If it is thoroughly 



♦Figures I, II and III are from my paper entitled "Woods and Tholr 

 Destructive Fungi," in the Popular Science Monthhj, August and Sep- 

 tember for 1886, and are used by permission of the editor, Trof. W. J. 

 Youmans. "• "• ^ • 



