28o 
Journal of Agricultural Research 
Vol. XXV, No. 6 
The original spore in these cases first germinated by the production of a 
germ tube that grew into a short mycelium, which in turn became a 
sporangiophore producing a group of sporangia. Some of the latter 
would then produce zoospores. 
chlamydospores 
Chlamydospores are produced directly from the mycelium, usually 
terminally, but sometimes intercalarily (PI. 12, C and D). They are 
spherical, granular like the conidia, but with a slightly deeper yellow 
shade (PI. 8, E). In pure culture they are produced in great abundance 
on oatmeal or potato dextrose agar. In the diseased rind of cacao fruits 
many thick-walled chlamydospores are usually produced (PI. 8, F). 
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Pig. 4. —Arrangement in desses of the ratios of the length to the width of conidia (cacao), showing the 
limits of variation. 
Measurements of chlamydospores. —The size of the chlamydospores 
is one of the criteria by which the species of Phytophthora are separated. 
Four hundred measurements were made of the diameters of the spores 
from both coconut and cacao strains grown on oatmeal agar. The coco¬ 
nut culture was 9 to 10 days old, and that of cacao was n days old. A 
summary of these measurements, grouped in classes, appears in Table III. 
The chlamydospores of the coconut strain varied in diameter from 
19.5 to 61.49 fx, the average diameter being 41.62 ju- These measure¬ 
ments were made in May, 1922, of spores grown on oatmeal agar and 
correspond favorably with those made in 1919 grown on com meal (7). 
For the cacao strain the chlamydospores varied in diameter from 17.5 
to 53.49 /x, the average diameter being 41.06 p. 
