102 
13. The minute almost microscopic pores making up the pore- 
layer. Study with the hand-lens. The basidiospores sift forth from these 
pores, and are often discharged in such quantities as to be visible to the 
naked eye, forming a white coating on the bark and leaves beneath the 
sporophore. 
Mount some of the spores (discharged or in crushed mounts of the 
the pores). Examine and OBSERVE :— : 
14. Their form, size and color. DRAW. 
Some of these spores, carried by the wind, find lodgment in dead 
branches or the stubs of broken-off limbs of their favorite hosts. Here 
they germinate sending forth a germtube into the dead host-tissue. This 
germtube develops into a mycelium which penetrates to the heart-wood 
where it spreads in all directions but most rapidly up and down, feeding: 
and accumulating a reserve of food. 
The character of this mycelium and its relation to the host-tissue can 
be best studied in prepared sections made through the region of the black 
line. Study the sections provided and OBSERVE :— 
15. The black line. Of what is it composed? 
16. The invasion of the medullary rays and wood-fibers sur- 
rounding the tracheae in advance of the black line. 
17. The character of the mycelium in the region of the black 
line and when advancing into uninvaded tissue. ; 
18. The character of the mycelium inside of the black line where 
the tissues have already been delignified. 
Make prawincs showing the above points. 
After a year or more, a sporophore develops from this mycelium, 
usually emerging from the old infection-court. The lower surface devel- 
ops a pore-layer which is annually renewed thereafter for many years. 
Examine the sporophore that has been sawed through and NoTtE:— 
19. That it is composed of many pore-layers or strata, one below 
the other, each succeeding one being more extensive than the preceding. 
Normally one layer is formed each year. DRAW. 
20. The rusty brown color of the inside of the sporophore with 
white flecks through it. 
21. The length of the pores, that is, the width of the pore-layer. 
Are the pores continuous from year to year? 2 
22. The shape of the pore-openings or mouths. Compare 
them, as to size and shape, with the pores of other species on the demonstra- 
tion table. 
Make a prawinc of the longisection through the sporophore; also an 
enlarged DRAWING to show shape and arrangement of the pore-openings. 
Make thin cross-sections of bits of the pore-layer and NoTE:— 
23. The mycelial structure of the pore-layer. 
_ 24. The basidia with spores lining the inside of the pores. 
Detail in a pRawinG the structures exhibited in the cross-section of a 
pore. 
The spores sift out of these pores and are disseminated by the wind. 
Make a diagrammatic DRAWING showing the pores in longitudinal section 
and the path of a spore in getting out of the tube. (See Buller’s book 
Researches on Fungi, p. 189.) ‘ 
Pathological Histology. Prepared cross- and longisections of wood 
from a living maple tree are provided. These have been stained to show: 
