1916] 
DUGGAR—THE TEXAS ROOT ROT FUNGUS 19 
on the surface of the roots, also those representing early 
stages of strand formation (fig. 2). 
(2) Strand hyphae. In these the individuality of the hyphae 
is practically lost, the strands being ultimately plectenchy- 
matic bands in which the individual cells vary considerably in 
diameter, the larger cells of young strands resembling some- 
what the larger hyphae above mentioned. It is interesting to 
observe that they may serve not only to spread the fungus 
vegetatively, but superficial soil strands may function as a 
conidial stroma. They are also more or less sclerotial and are 
doubtless an important factor in the persistence of the fungus 
in the soil (fig. 3). 
(3) Acicular type. The arachnoid mycelium with which 
the root is invested gives rise to certain fairly rigid hyphae 
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. 3. Phymatotrichum omnivorum: mycelial strands; upper, 
old strand from root of cotton; lower, young strand from conidial 
area. 
which in turn produce branches that are most frequently in 
pairs, that is, opposite, and at right angles. Branching 
is also not infrequently verticillate. In all cases such branches 
are characteristic in appearance, being rigid and needle-like, 
tapering to very fine filaments (fig. 4). This type has been 
found only on the roots. 
It is necessary to add, however, that intermediate types 
between the various forms mentioned occur. In general, the 
