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of cases the corms and cormels from a diseased corm are diseased, the 
fungus is thus perpetuated without the intervention of a spore-stage. 
Just how the fungus passes from the old corm to the new one is unknown. 
It does not grow directly from the one to the other but either works along 
the sheathing leaf-bases or grows out into the soil from whence it at- 
tacks the new corm or cormels. 
The fungus is known to winter in the soil, hence the possibility that soil 
containing mycelium of the pathogene may be splashed by rain onto the 
foliage. The foliage is often beaten down onto the soil where infection 
may occur. The latter is much more likely to occur with the tops of 
seedlings or cormels than of older plants. Why? 
Healthy corms set into infested soil are doubtless commonly infected 
by the pathogene there. 
Pycnospores have been found in the spring in pycnidia on leaves which 
have remained out of doors all winter, but only in very limited numbers. 
These pycnospores will germinate and may constitute the primary inocu- 
lum for the foliage of seedlings or cormels; by the washing of these spores 
into the soil they may infect the corms themselves. 
Pathogenesis. Of the three probable sources of primary inoculum, 
diseased corms, infested soil or pycnidia in overwintered foliage, the last 
is most readily studied. Examine some of the leaves gathered in the 
autumn. OBSERVE :— 
12. The old lesions on the leaves. 
13. The presence of numerous, black elevations,—the pycnidia. 
Is there an ostiolum? DRaw, showing pycnidia on the leaf. 
With the needle remove several pycnidia to a drop of water on a slide, 
cover and study under the low-power. Pressing lightly on the cover with 
a needle, OBSERVE :— 
14. The many pycnospores; size, shape and number of septa. 
The mycelium in the diseased tissue of the corm is not easily detected. 
Make thin sections from the material provided. Stain with methylene blue 
in weak acetic acid for one hour. Wash thoroughly and study. OBSERVE: 
15. The large cells still partly packed with starch-grains. 
16. Between them the small blue-stained mycelial threads, 
varying in thickness with the space at their disposal. 
DRAW a few host-cells with the intercellular mycelium. No fruit- 
bodies or spores are known to be produced on diseased corms. 
On infected leaves, pycnidia appear in the lesions simultaneously with, 
or soon after the lesions become evident. Study the pycnidia in section, 
using prepared slides. OBSERVE :— 
17. The outer wall of pseudoparenchymatous tissue. 
18. The inner layer of thinner-walled cells from which arise 
the conidiophores. 
19. The conidiophores bearing pycnospores. 
20. The mycelium in the tissue of the host. 
DRAW, showing the structure of a pycindium seen in longisection. 
The pycnospores from the primary lesions on the leaves initiate secon- 
dary cycles. ; — ite 
Saprogenesis. The fungus is able to live in the soil without the 
presence of the living host for at least four years. Whether it feeds on 
organic matter and develops in the soil or merely remains alive in a dormant 
condition until corms of gladioli are again available for attack, is not 
