ENDOTHIA PARASITICA AND RELATED SPECIES. 75 
by reason of the weakened condition of the chestnut trees. Others 
believed it to be of foreign origin. Its recent discovery in China 
and Japan has settled this question. 
To determine positively the identity of the organism, a thorough 
study was made of the types or authentic specimens of all the species 
of Endothia obtainable. Asa result of this work a revision of avail- 
able species of the genus is presented. This is based upon the field 
and laboratory study of over 600 collections. Over 4,000 cultures 
have also been studied. , 
Endothia gyrosa (Schw.) Fr. is the type of the genus, which is 
naturally divided into two sections, chiefly by the character of the 
ascospores. In section 1 they are short, cylindric to allantoid, and 
continuous or only pseudoseptate. This section contains two species, 
E. gyrosa and EF. singularis. 
Section 2 has oblong-fusiform to oblong-ellipsoid uniseptate as- 
cospores. This contains four species and one variety, Endothia 
fluens, EF’. fluens mississippiensis, E. longirostris, E. tropicalis, and 
E. parasitica. I. tropicalis is a hitherto unrecognized species. 
Radiating layers of yellowish or buff mycelium situated in the 
bark and cambium of the host are found to be constant and dis- 
tinctive characteristics of Endothia parasitica. None of the other 
species studied shows this character. 
All species of the genus possess a stroma having a distinctive 
yellow to reddish color. 
There is no division of stroma into distinct layers, as described by 
some authors. Pycnidia or perithecia may arise in any portion of 
the stroma. Most commonly where pycnidia and perithecia are both 
present the pycnidia are above the perithecia, though the reverse 
arrangement is sometimes observed and all intermediate conditions 
frequently occur. 
‘The stromata of the species of section 1 are larger, more erumpent, 
and contain more numerous pycnidia than those of section 2. Hn- 
dothia singularis is especially striking in this respect. The stromata 
of section 2 are smaller and very similar in all the species. 
The pycnidia consist of more or less irregular chambers or locules 
in the stroma. ; 
The pycnospores are small in most species and furnish no very 
distinctive specific characters. The pycnospores of Endothia trop- 
icalis are, however, constantly larger and more variable in size than 
those of the other species. 
Paraphyses have been described by some authors, but have never 
been observed by the writers. er ae 
The ascospores in the species of section 1 are very similar in size 
and shape. Those in section 2, though similar, have been found by 
thorough study and careful measurement to show constant though 
