47 
ium.) Are the cells penetrated? If available, study the mycelium growing 
in agar. 
DRAW to show the mycelium in the fruit and its relation to the cells. 
This mycelium soon amasses at certain points beneath the skin of the 
fruit and bursting the skin pushes forth a cushion of short branched 
conidiophores. Make thin sections through these cushions,—sporodochia, 
and the skin of the fruit (or use prepared slides), study and OBSERVE :— 
26. The cluster of conidiophores protruding through the rup- 
tured epidermis. The cuticle of the fruit pushed back on either side. 
_.. . 27. The densely packed mass of mycelial cells from which the 
conidiophores arise,—the stroma. Note the pseudoparenchymatous struc- 
ture. 
28. The conidiophores; their form and mode of branching, 
length and diameter, color, contents and septation. (Use material from 
the petri-dish culture.) 
29. The conidia; their mode of formation,—moniliform. It was 
from this character that the conidial stage first received the name Monilia. 
Make a careful prawinc of the section through the sporodochium 
to show its structure and relation to the host. ; 
From the diseased fruits, especially if attacked when green, the my- 
celium may penetrate through the cortex of the fruit-pedicle to the bark 
of the twig and cause twig-blight. Then passing on down to the larger 
limbs, it spreads into the bark and initiates the large limb-cankers. 
Saprogenesis. Many of the rotted or mummified fruits fall to the 
ground in the autumn or cling to the tree. Those on the tree may, as 
already seen, harbor the parasite throughout the winter. Those which 
fall to the ground become more or less buried in the soil and in them just 
beneath the cuticle in the epidermal regions is formed a crust-like black 
stroma. Make sections (or use those provided) through the skin of one of 
these fallen black mummies. Study and oBsERVE:— 
30. The black thick-walled cells of the stroma. Their relation 
to the old dead host-tissue. DRaw. 
From this stroma there arise in the spring the apothecia, the external 
features of which have already been studied. Examine a thin section 
through the apothecium and OBSERVE :— 
31. The densely packed hyphae making up the greater portion 
of the section,—the excipulum. This is made up of much septate inter- 
woven threads of the mycelium. It forms the bulk of the apothectum 
and serves as a protection and foundation for the layer of asci that lines 
the cup,—the hymenium. 
-- 32. The make-up of the hymenium; the long slender tube-like 
asci containing the ascospores. How many ascospores in each ascus? 
Their form and structure; the thread-like paraphyses standing up between 
the asci, septate or not? 
The paraphyses at first form the hvmenium but as the apothecium 
expands the asci are formed and push up between the paraphyses and 
bécome a part of the hymenium. Make out the pore at the apex of the 
ascus. Confirm your observations with the prepared slides. 
Make DRAWINGS to illustrate fully the structure of the apothecium. 
REPORT 
1. Prepare a graphic illustration (cartoon) showing the life-his- 
tory of Sclerotinia cinerea (Bon.) Wor. 
