99 
the center of the perpendicular pore from which they fall and are then 
caught by the wind and blown about in all directions. (Buller, Researches 
on Fungi, p. 133-152). If material of discharging spores is available, 
NOTE :— 
11. The clouds of spores falling from the sporophore. DRAW. 
12. The deposit of white spores on the black paper under the 
sporophores. 
Mount some of these spores in water and under the microscope, 
OBSERVE :— 
13. The size and shape of the spores. DRAW. 
The sources of the primary inoculum are the shelving or resupinate 
sporophores produced in great abundance on the outside of diseased trees. 
In the material provided, NoTE:— 
14. That the fruit-bodies are perennial. 
15. The black, checked upper surface of the pileus in the case 
of the shelving form. 
16. The dull-brown pore-layer,—the compound hymenium. 
17. The small round pores making up the pore-layer. 
DRAW a Shelving and resupinate fruit-body. 
Make freehand sections of a fruit-body. provided, stain with eosin, 
mount and examine with the microscope. OBSERVE:— 
18. The character of the mycelium forming the trama of the 
pileus and the substance between the pores. DRAW. 
19. The subhymenium and the two kinds of cells produced 
in the hymenium, basidia and setae. DRAW. 
20. The form of the basidium; the four spores borne on each. 
DRAW. 
If material does not show points mentioned above, see Veg. Phys. 
and Path. Div. Bul. 25, pl. TX, fig. 3. copy. 
If the spores reach the exposed heart-wood of susceptible conifers, 
they germinate under favorable conditions and the mycelium extends 
down into the trunk of the branch. Why are exposed wounds in the sap- 
wood of conifers not infected? 
The mycelium usually confines its activities to the annual rings first 
invaded, extending longitudinally and circumferentially in these rings 
much more rapidly than radially in the wood. Thus, completely decayed 
rings in the wood often result as the first evidence of disease. This is the 
ting-shake symptom. Soon, however, the mycelium invades the rings 
of wood adjacent to the shake and spreads inward and outward toward 
the sap-wood. The progress outward depends upon the amount of resin 
present (ic. in pine). The mycelium rarely penetrates the sap-wood. 
In spruce, however, it not only decays the sap-wood but penetrates and 
kills the tissues of the bark and produces small sporophores in the fissures 
of the bark. 
Saprogenesis. The ring-shake fungus may live in the wood of 
susceptible conifers after the tree is dead. Fruiting bodies are formed 
also in the saprophytic stage and furnish inoculum for new infections. 
Saprogenesis is not an obligatory stage, however, for the production of 
- anything in the life-history of the fungus which is not produced in the 
living tree. ' 
Secondary Cycles are not considered as existing in cases of wood-rot path- 
ogenes since only one source of inoculum is developed annually. The period 
