18SG.] NEW YORK ACADEMY OF SCIENCES. 113 



the rings, whicli it reiidily follows. Piiinting the ends of the 

 timber offers bnt little ])rotection if the slightest opening occurs, 

 as a spore can enter, grow, and carry on its destruction for a 

 long time before it shows exterior decay. 



The structure of eacii longitudinal cell of this wood con- 

 sists of three lamelhB, a tliin inner one surrounding the lumen, 

 then a thicker one, then a tliin outer one which joins that of the 

 adjacent cell. Chemicals which dissolve the latter do not attack 

 the otiier two, and vice versa; thus they can be sejnirated. In 

 the decay of this wood induced by tlie fungus described, the outer 

 layer seems to be the last destr.jyed in many of tlie cases I have 

 studied. 



The decay of the yellow pine is a matter of increasing import- 

 ance to many of the railroads in this vicinity, as they are dejiend- 

 ingmore upon the use of this timber for ties than formerly, while 

 for bridge timber and ])lank it is indispensable; and it would be 

 difficult to supply its place in the construction of the frames of 

 cai's. 



The mycelium of Le7iUnus hpideus Fr. is composed of 

 small branching filaments measuring from one to two micro- 

 millimeti-es in diameter. With the mycelium I generally find 

 an abundance of crystals of one form of oxalate of lime. Some- 

 times small imbedded cells of other fungi are seen; also other 

 minute forms in adherent masses, the individual cells being (piite 

 beyond the definition of i)resent microscopes. These lower 

 species which act as the allies of Lcutinus are difficult to trace. 

 The destructive power of this fungus is very gi-eat. and it is 

 causing enormous losses to users of timber, which are not 

 realized or even suspected. 



The remaining species of fungi in my list are those which I 

 have thus far identified as inducing the so-called ^' dry rot" in 

 various woods. Polypnrus versicolor Fr. is very common, as 

 I find it upon the sap-wood of the white and red oak, and chest- 

 nut ties; also upon the sap-wood of chestnut and locust posts, and 

 on the sap-wood and heart-wood of wild chei-ry, and once on 

 hemlock boards. As a rule, it is more abundant on sap-wood of 

 the oak than on chestnut ties. My observations refer to the 

 entire length of the Boston and Albany R.R., and parts of many 

 other roads in Massachusetts. On tlie heart- wood of the 

 Avhite oak ties, I have only identified Polyporus applnnaius Fr., 

 which also attacks the sap-wood of many otiier kinds. The 

 heart-wood of chestnut ties is not so quickly attacked by fungi as 

 some other woods, since most of them are removed on account of 

 mechanical destruction of the fibres under the rails before decay 

 takes ])hice. I have several samples of the mycelium in chestnut 

 tie (this one from the yard of the Grand Central Station), but 



