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. As a 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 E . singularis. 



Section 2 has oblong-fusiform to oblong-ellipsoid uniseptate as- 

 cospores. This contains four species and one variety, Endothia 

 fluens, E. flioens mississippiensis, E. longirostris, E. tropicalis, and 

 E. parasitica. E. 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. En- 

 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. 



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 



