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SECTION OF VEGETABLE PATHOLOG®. 337, 
brown), flexuose, often anastosmosing, septate, and varying in diame- 
ter from 1.5 to 3 uw (1u=gste5 Of aninch). Itis through the action of 
these mycelial threads on the cell contents of the host that the exter- 
nal characters of the disease, already noted, are produced. 
Reproductive system.—The reproductive system of Spheerella fra- 
garice is quite complex, and although it has been studied very care- 
fully it is not yet fully understood. From our examinations of the 
material at our disposal we have been able to determine three spore 
forms and possibly a fourth; the three of which we feel sure are coni- 
dia, spermatia, and ascospores. We are yet doubtful in regard to the 
pycnidia. 
Conidia (Figs. b and c).—The best known and doubtless the most 
important reproductive bodies, economically considered, are the con- 
idia. After the mycelium has grown for a time within the leaves and 
the light-colored central areas of the spots appear, the threads occu- 
pying this portion become massed together at frequent points just 
_ beneath the cuticle of either surface, and from these masses numer- 
ous short, colorless branches are sent out either through the stomata or 
ruptured cuticle, and it is upon their free ends that the earlier de- 
velopment of conidiatakes place. Thelengthof the branches variesa 
good deal, but usually ranges between 304 and 504; they are sometimes 
composed of a simple elongated cell, but often they are divided by 
transverse septa into two to several cells. Ata later period in the 
development of the fungus, conidia-bearing branches may arise from 
the perithecia, described below. 
On the free ends of the branches the young conidia are developed, 
first as minute globose bodies, but, rapidly elongating, they soon ap- 
a as illustrated in Plate I, Fig.b. Sometimes a succession of spores, 
eld together in a single series or chain by their contiguous ends, are 
formed upon a single stalk, and sometimes, though very rarely, two 
such series are developed from the apex of a common support. The 
free apex of the terminal conidium, whether it stands alone or forms 
one of a series, is obtuse and rounded; the other end and the ex- 
tremities of those standing intermediate in a series are flattened at 
the points of attachment. Their length is from 20u to 50, and they 
have a diameter of from 2.54 to 44. Often only one-celled, they are 
frequently divided by transverse septa into two or three cells. They 
are colorless, like the stalks which support them, and are filled witha 
transparent, slightly granular fluid. The formation of these con- 
idia continues throughout the summer, under favoring conditions of 
moisture and heat, and as they are exceedingly light and germinate 
readily in water, the rapid spread of the fungus and consequent dis- 
ease over a plantation or section of country is easily understood. This 
stage of the fungus has been named Ramularia fragarice by Charles 
H. Peck, and Ramularia Tulasnei by Saccardo. 
At the approach of cold weather the formation of the conidia ceases, 
but the mycelium of the fungus remains alive in the tissues of the 
leaves, and in early spring a few warm days are sufficient to bring 
forth a new crop ready to spread infection at the first opportunity. 
When the conidia are sown in water at atemperature of about 60° 
¥.., they. will in a few hours send out slender germ tubes, which in- 
increase rapidly in length by continued apical growth. In forty-eight 
hours the germ tubes attain a length of many times that of the con- 
idium from which they start, and are usually several times branched. 
Waiter is necessary to effect germination. 
AG 87——22 
