DESCRIPTION OF PLATES. 39 



ray cells have been destroyed; m, cross sections of hyphse of Ceratostomella pilifera. 

 3. Cross section of a medullary ray, with resin duct showing the internal cell 

 walls wholly dissolved out. Masses of brown hyphse, m, of the ''blue" fungus 

 extend longitudinally through the ray. 4. Young perithecium of the ' ' blue ' ' fun- 

 gus ( Ceratostomella pilifera (Fr. ) Winter), grown on pine agar culture. 5. Mature 

 perithecla of the " blue" fungus ( Ceratostomella pilifera (Fr.) Winter), grown on 

 pine agar culture, showing the spores, s, discharging from the top of the beak. 

 The line at the side equals 0.1 mm. 6. Two perithecia of the " blue " fungus 

 ( Ceratostomella' pilifera ( Fr. ) Winter) just before the discharge of the spores. Peri- 

 thecia from culture on pine wood. 7. Two asci with spores of the ' ' blue ' ' fungus 

 ( Ceratostomella pilifera (Fr. ) Winter). 8. Spores of the " blue " fungus ( Ceratosto- 

 mella pilifera (Fr.) Winter). 9. Top of beak of perithecium of Ceratostomella 

 pilifera (Fr. ) Winter, just after the discharge of the spore mass. The hyphae 

 composing the tip of the beak have spread out, forming a sort of support for the 

 spore mass. 10 and 11. Median sections of sporophores of the "red-rot" fungus 

 ( Polyporus ponderosus, n. sp. ) , natural size. 



PLATE VIII. Photomicrographs showing the structure of "blue" wood. Fig. 1. A 

 radial section, showing how the hyphse of the "blue" fungus grow in the medul- 

 lary rays, being confined almost entirely to the rays. Magnification, 80 diame- 

 ters. Fig. 2. A tangential section, showing how the hyphse completely fill the 

 medullary rays. Numerous small hyphae grow out into adjoining cells in a 

 tangential direction. This makes the wood cells in the photograph look as 

 if they were septate. The apparent septa are hyphre. Magnification, 80 

 diameters. 



PLATE IX. A number of pieces of wood from the bull pine (Pinus ponderosa) , show- 

 ing holes made by wood-boring beetles. The trees from which these pieces were 

 taken were in most cases dead, either standing or felled. The "blue" fungus 

 has started to grow in the wood cells bordering on these holes, and is gradually 

 spreading to other cells from these holes as a center. Note that these wood 

 pieces show both radial and tangential surfaces. The piece of wood in the 

 center at the bottom of the plate is western hemlock. 



PLATE X. Sections of "black-top" trees of the bull pine (Pinus ponderosa) , showing 

 early stages of the "red rot" caused by Polyporus ponderosus, n. sp. Fig. 1. 

 Section of a dead tree 35 feet up from the ground. This tree had probably been 

 dead for eighteen months to two years. The decay has just started in at several 

 points on the north and northwest sides of the tree. Note that the larger part 

 of the wood is blue. The healthy, unaffected wood is white. Note also the 

 beetle holes in the bark. Fig. 2. A section from a similar ' ' black-top ' ' tree, 

 showing a more advanced stage of decay. The whole section was blue. The 

 decay started on the side where the bark prevented the rapid evaporation of 

 moisture from the wood and had reached the heartwood. Note the radial and 

 tangential sheets of white mycelium. Fig. 3. A section from the same tree from 

 which fig. 2 was taken, made some 15 feet higher up. The section is blue, but 

 shows few signs of decay. This shows how the "red rot" usually attacks the 

 tree somewhere below the crown. 



PLATE XI. Sections of "black-top" trees of the bull pine, showing advanced stages 

 of decay caused by Polyporus ponderosus n. sp. Figs. 1 and 2. These two sections 

 were cut from a fallen top of a "black top " such as is shown in PI. XIV, fig. 1, 

 one near the point where the top broke off, the smaller one near the top of the 

 crown. Both show how completely the wood has been destroyed. This stage 

 was probably reached about three years after the beetle attack. Fig. 3. The 

 lower figure shows a section cut 4 feet from the ground from a standing " black- 

 top" pine. On one side a fruiting body of Polyporus ponderosus is to be seen, 



