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The Primary Cycles are initiated in the early spring when the buds 
swell and begin to open, by inoculum which has overwintered on the hairy 
bud-scales. Presumably this inoculum is some kind of spores; just what 
kind and how they teach the bud-scales is not known. ; 
Pathogenesis. Examine the buds on the peach twigs provided. 
OBSERVE :— 
8. The hairy character of the outer bud-scales. Remove one 
and study it under low-power. Minute globose spores may sometimes 
be detected, lodged among the long hairs on the scale. These may belong 
to the leaf-curl pathogene, at least present evidence warrants the belief 
that such spores lodged in this way serve as the primary inoculum. Make 
an enlarged diagrammatic SKETCH of an infested bud. 
The spring rains which cause the buds to swell and to open, also cause 
the spores to germinate and send forth a slender germtube which enters 
the bud between the scales and penetrates the tender leaves. As the leaves 
develop, the mycelium within spreads between the cells and stimulates 
the growing tissue, resulting in a curling and fluting of the blade. The 
germtube may also penetrate into the growing tissues of the developing 
twig. 
Make thin sections through diseased leaves or twigs; clear in chloral 
hydrate; wash and stain for some time in eosin or methyl blue; wash and 
mount in water. LOCATE:— 
9. The intercellular mycelium, fitting tightly in, and conforming 
with the intercellular spaces. No haustoria are formed. DRAW a bit of 
the mycelium with adjoining host-cells. 
Branches of this mycelium pass toward the surface between the epider- 
mal cells. Make thin tangential sections from the surface of the diseased 
leaf. Stain as above and study under the high-power. MAKE OUT:— 
10. The very abundant subcuticular mycelium; its irregular 
septate form; its branching and anastomosing habit. From this mycelium 
arise the asci. DRAW. 
Study cross-sections (freehand or prepared) of a leaf through a lesion 
bearing asci. OBSERVE :— 
11. The row of enlarged’ and angular epidermal cells of the host; 
their organs and contents. 
12. The layer of long, more or less angular asci, containing spores, 
standing at right angles on the epidermal cells. 
In the prepared slides, oBSERVE:— 
13. Some of the asci, small and young with deeply stained 
protoplasmic contents and nuclei. 
14. Mature asci containing deeply stained ascospores or empty; 
shape and size of the spores; number in an ascus. 
DRAW a portion of the epidermis showing asci, old and young, in dif- 
ferent stages of development. 
15. That these ascospores often increase in number within the 
ascus by budding like yeast (known by the large number of small spores 
which the asci contain). DRAW. 
Saprogenesis. The ascospores when mature are shot through a 
rupture in the top of the ascus. Their further history is unknown. The 
mycelium in a lesion produces but one crop of ascospores and then ap- 
parently dies with the leaf which soon falls to the ground. There is prob- 
ably some saprogenic activity on the part of this pathogene between the 
