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92 MISSOURI BOTANICAL GARDEN. 
at the top. The stalks vary in height from 1 to 2mm., 
averaging 1.5 mm., with anaverage diameter of 25u. The 
heads, when enveloped in mucus, are globular and measure 
from 40 to 600u in diameter; without the sheaths they 
are flattened oval or fungiform, and measure 30 to 200. 
They are colorless at first, but later change to gray or 
green. When a stalk is broken off before maturity, it 
often sends out small branches, either of single hyphae or 
of clusters of hyphae, bearing conidia. 
SECONDARY CONIDIA. 
The secondary conidia are usually elliptical in shape, and 
measure 3.6u by 1.8y, average. They are hyaline, color- 
less, and are borne both terminally in close clusters and 
on simple hyphae, and in a short time fall off and adhere 
together, thus forming miniature heads (pl. 9, f. 9). 
PRIMARY CONIDIA. 
The primary conidia are elliptical in shape, and are borne 
terminally on branched hyphae (pl. 9,f. 10). They meas- 
ure 3.8u by 1.64, average. They are hyaline and colorless. 
In some cases, where the upper portion of the stalk or 
head has been broken off new stalks sprout out from the 
region of the apex in the old one. Branches are also 
formed without injury. 
The fungus penetrates deeply into red gum boards, giv- 
_ing-them a dirty appearance, rendering them unfit for 
making the best grade of boxes, crates, etc. It permeates 
the medullary rays and many of the larger and some of the 
smaller vessels of the wood. The mycelium in the wood is 
generally of a color varying from gray to brown or dark 
green. 
Graphium rigidum (Pers.) Sacc. 
A species of Graphium was found discoloring the Sap- 
