36 BULLETIN 380, U. 8S. DEPARTMENT OF AGRICULTURE. 
PHYSIOLOGY. 
CULTURAL STUDIES.’ 
During the past three years the writers have had under observation 
more than 4,000 cultures of the several species of Endothia on niore 
than a dozen artificial media, as well as on sterilized twigs of many 
kinds. Throughout this work the writers have been impressed with 
the uniformity of the behavior of the organism in culture and the 
certainty with which the various species could be distinguished on 
any of the media used. 
Cultures of Endothia parasitica, for instance, from specimens sent 
from China or British Columbia were absolutely indistinguishable 
from cultures made on the same medium from local material. 
Transfers made from stock cultures which had been kept on artifi- 
cial media for two years were identical with transfers from freshly 
collected material. The same remarkable constancy held for the 
other species. Cultures from material collected in different localities 
or from different hosts were identical, not only in appearance but, so 
far as the writers were able to determine, in temperature and moisture 
relations also. As previously noted, this is in marked contrast to the 
senior writer’s experience with the species of Glomerella and it is 
believed differs from the experience of many investigators of fungi. 
No less striking is the certainty with which the several species may 
be distinguished on any medium tried. Endothia parasitica, E. 
tropicalis, and #. fluens and its variety mississippiensis are very 
closely related morphologically. Moreover all except 2’. parasitica 
have, as near as could be determined, much the same relation to their 
hosts. Yet each species has distinctly and readily recognized charac- 
ters on culture media. 
| It should not be imagined, however, that the differences are 
recognizable at once as clearly distinctive characters. The differences 
at first glance might readily be considered fluctuating variations. 
But the fact that the characters remain constant through hundreds 
of generations and have never varied toward one another makes 
them worthy of recognition as specific characters. 
In a previous paper (77) the writers described their results with 
cultures of E'ndothia parasitica, EF. fluens, FE. fluens mississippiensis, 
and £. gyrosa on a number of culture media. At that time the work 
of other investigators was reviewed and the methods of preparing 
the various culture media and making the cultures described. Since 
the publication of that paper, however, cultures of two more species, 
E. tropicalis and E. singularis, have been secured and about 2,000 
additional cultures of the various species made. In addition to the 
culture media mentioned in the previous paper (77, p. 10), the writers 
1The cultures described were all grown at ordinary laboratory temperatures in the 
winter, about 20° to 24° C, 
