76 
14. The mass of conidia oozing from each mature acervulus; 
color and consistency of the mass. Remove a spore-mass to a drop of 
water; note the dissolving effect. The conidia are held together by a gela- 
tinous substance which quickly dissolves in water. (See_illustration 
photograph; Pl. Ind. Bur. Bul. 93, pl. VI, fig. 1A; Illinois Bul. 118, pl. 
III, fig. 2 and pl. V, fig. 1; Pl. Ind. Bur. Bul. 44, pl. I, II and VI.) These 
conidia initiate secondary cycles. 
Make a careful DRAWING of several acervuli as they appear under the 
hand-lens. ; 
Make a number of very thin sections through a bit of the affected tissue 
showing mature acervuli (or use prepared sections). Study and OBSERVE -— 
15. The great mass of conidia pushed forth through the rup- 
tured epidermis, the recurved edges of which show at each side of the 
spore-mass. 
16. The mycelial bed, forming the base of the acervulus, from 
which the short simple conidiophores arise. How are the conidia formed? 
17. The mycelium ramifying the adjoining host-tissues; inter- 
or intracellular? 
DRAW to show the structure of the acervulus and its relation to the host- 
tissues. 
Saprogenesis. With the mummification of the fruit and the death 
of the bark in the cankers, the mycelium does not die but sometimes 
continues a saprophytic existence. It lies dormant through the winter, 
resumes its activities in the spring and usually produces acervuli, though 
sometimes the sexual fruit-bodies, perithecia, are produced. The latter 
arerare. Acervuli having been studied, a brief examination of the perithe- 
cium may be made. Study the prepared sections. OBSERVE :— 
18. The long blunt protuding beak of the perithecium. 
19. The relation of the perithecium to the host-tissue. 
20. The asci; form and arrangement in the perithecium. 
21. The structure of the perithecial walls. 
22. The ascospores; number and arrangement in an ascus; form. 
DRAW a longisection of the perithecitum. The ascospores, when ‘pro- 
duced, doubtless serve to initiate primary cycles. 
Secondary Cycles are initiated repeatedly throughout the growing- 
season on fruits and twigs, causing fruit-rot, twig-blight and limb-cankers. 
The pathogene passes through the same forms and phenomena as in the 
primary cycles. 
Pathological Histology. Slides are provided showing sections through 
young spots such as are to be observed on the fruits in the jar. Study the 
sections and praw to show pathological effects observed. Explain the 
formation of the cork-layer. 
REPORT 
1. Make a diagram illustrating the cycles in the life-history of 
Glomerella cingulata (Stonem.) S. and von S. 
