1918] 
BURT—CORTICIUMS CAUSING PLANT DISEASES 127 
None of the vertical sections of leaves bearing fructifications 
of C. Stevensii have yet shown vegetative hyphae in the in- 
tercellular spaces of the leaves, although I have made sev- 
eral sets of preparations expressly for the demonstration of 
such hyphae. А set of preparations from the petiole of a 
pear leaf well-coated with the fungus did not show hyphae 
in the interior of the petiole. Microscopic characters of C. 
Stevensu and C. koleroga are within the limits of fluctuation 
of a single species. In connection with the collections on 
Codiaeum Dr. Rorer wrote, ‘‘This thread blight occurs here 
in the damp valleys every year and takes quite a toll of 
erotons, nutmegs, and many decorative plants, even roses."' 
Specimens examined: 
North Carolina: Horseshoe, J. G. Hall, comm. by F. L. 
Stevens, sclerotial stage on pear twigs; Mt. Airy, F. C. 
Reimer, comm. by F. L. Stevens, fertile stage on pear 
leaves. 
Georgia: A. L. Quaintance, comm. by F. S. Earle, sclerotial 
stage on apple twigs. 
Florida: C. G. Lloyd, sclerotial stage on pear twigs. 
Texas: Dickson, F. W. Mally, comm. by U. S. Dept. of Agr., 
sclerotial stage on pear twigs. 
Trinidad: Diego Martei, J. B. Rorer, fertile stage on leaves 
of Codiaeum variegatum (in Mo. Bot. Gard. Herb., 44771) ; 
Petit Valley, J. B. Rorer, sclerotial and fruiting stages on 
leafy twigs of Codiaeum variegatum (in Mo. Bot. Gard. 
Herb., 11960, 19786, 19810, and 20062). 
Corticium vagum Berk. & Curtis is another parasitic Cor- 
Hciwm, which belongs in the section with the preceding 
species by reason of the structure of its fructification. In 
contrast with the mycelium and sclerotia upon stems of the 
portions of the host above ground in the preceding species, 
C. vagum has its mycelium saprophytic in the soil and be- 
coming parasitic and sometimes forming sclerotia on sub- 
terranean portions of host plants, such as roots or under- 
ground stems,—presumably an adaptation to the climatic con- 
