2 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 
conclusively that the disease is spreading very rapidly, especially 
west and south from New York and also north and east. 
The exact identity and relationships of the fungus causing the 
disease and the origin of the epidemic soon became the subject of 
study by various mycologists and pathologists. Different explana- 
tions were offered for the sudden appearance and behavior of the 
disease, one view being that the fungus was probably a foreign 
parasite which had been introduced ; another, that the organism was 
probably a native species which had recently attracted attention, 
chiefly by reason of the weakened condition of the chestnut trees 
due to abnormal climatic or other conditions. 
In attacking the problem of the origin of the parasite and its pos- 
sible control, it was evidently necessary to secure all the information 
possible in regard to its life history, identity, distribution, and re- 
lationships. The senior writer in an unpublished paper prepared in 
1908 pointed out the close relationship and possible identity of 
Diaporthe parasitica with certain species of Endothia. Clinton (16) 
and Farlow (28) soon after also made the same suggestion. Two 
species of Endothia had already been described from this country 
by Schweinitz (74) under the old generic name, Sphaeria. These, 
however, had in recent years been regarded as a single species and 
referred to Endothia gyrosa (Schw.). Owing to a lack of knowledge 
of the types of these two species and for want of good specimens 
showing ascospores, it was difficult to determine what species of 
Endothia were indigenous in the eastern United States. Since it 
had been suggested that Diaporthe parasitica was either identical 
with one of Schweinitz’s species or a mere variety of it, the present 
writers undertook a thorough study of the genus Endothia in its taxo- 
nomic, ecological, and pathological relations. It was first necessary 
to determine the identity of the two species already described by 
Schweinitz from America and also to learn their distribution and 
host relations. As one or both of Schweinitz’s species were reported 
to occur in southern Europe on chestnut, it was important to obtain 
exact knowledge in regard to the identity and relationships of the 
European species. The senior writer spent several months in Eu- 
rope collecting material of Endothia in the field and etudying her- 
barium specimens, of types and authentic collections of Schweinitz 
and other authors. Material was also acquired by collection and 
exchange with pathologists and mycologists in nearly every region 
of the world in which Endothia was known to occur. Comparative 
cultural studies were made of all the living material secured, as well 
as inoculation experiments on various hosts. The recent discovery of 
the typical chestnut-blight parasite, Endothia parasitica, by Meyer 
(27, 76, 78), in China and Japan and the failure to find in Europe or 
America any native form which would produce the disease appear 
to settle beyond question its foreign origin. 
