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THE POPULAR SCIENCE MONTHLY. 



The affected wood looks dark and moldy, and, upon close examina- 

 tion, the little beaks, about one eighth of an inch long, can be seen 

 projecting from the wood, and, when it is dressed, will show discolor- 

 ation ; if dried, the further growth of the fungus is arrested, but will 

 be resumed if the wood becomes damp. On examination with the 

 microscope, the resin-ducts of the medullary rays (see Fig. 11) will 

 be found filled with the dark-colored threads, spreading to the upright 

 ducts and the wood-cells. Although the dark threads are abundant, 

 discoloring the wood, they alone do not destroy the canals, but are 

 aided by fermentations. 



Fig. .18 shows some of the cultivated ferments I obtained from 

 splitting open a block and touching a sterilized needle to a resin-duct 

 destroyed by Sphwria pilifera (Fr.), and then inoculating a culture- 

 tube of prepared gelatine. It will be recognized as a species of /Sac- 

 charomycetes, but with more elliptical cells than Saccharomycetes cer- 

 visice, the yeast-plant. In wood further advanced in decay than the 

 destruction of its resin-ducts, rounder cells have been frequently ob- 

 tained by direct observation with the microscope. 



Some species of the SpkcEria played important parts, infinitesimal 

 though they were, in inducing the fermentations which helped decay 

 the Nicholson pavement ; for in the partially decomposed white-pine 

 blocks I find generally an abundance of the dark hypha, and, in some, 

 the fragments of perithecia, showing it was a Sphceria that produced 

 the dark filaments, and not a modification of the white mycelia of 

 some of the higher fungi which are often found associated with it, or 

 in other portions of the block. The decayed spots in the white cedar 

 before described are more or less filled with the dark-colored hypha of 

 some species of Spharia. 



Fig. 17, f . 



Fig. 18. 



Fig. 19, magnified ten diameters, represents Sphceria aqitila (Fr.), 

 " Brown nestling Sphseria," very common on limbs on the ground the 

 mycelium pierces and discolors the wood-cells. An asci containing the 

 ascospores, magnified fifty diameters, is shown in the left side of the 

 figure. 



Sphceria morbosa causes the black knot in plum and cherry trees. 



In Fig. 20 are represented a few of the filaments and the dark 



* From " Fungi : their Nature and Uses," by M. C. Cooke, M. A., LL. D., vol. xv of 

 " International Scientific Scries." 



