48 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 
growth at 27° C. was apparently equal to that at room temperature. 
At 22° C. (room temperature) all species developed much more rap- 
idly than at the lower temperatures. At 17°, 12°, and 9° C. there 
was progressively less and less growth. At 7° C. and lower there 
was no growth whatever. _ 
While these tests are not wholly satisfactory and must be regarded 
only as approximations, they are of some interest. Below 7° C. there 
is no growth in any species. 
It is evident that there is a considerable range of temperature, 
from below 20° to well above 80° C., within which the species of En- 
dothia grow readily. Within this range there may be a definite 
optimum for each species, but this has not yet been determined. For 
Endothia parasitica the optimum appears to be at 27° C. or above, 
and the same may be true of the other species. 
At 40° C. or above no growth occurs. There is considerable evi- 
dence, however, that E'ndothia fluens is less resistant to the higher 
temperatures than either £. parasitica or E'. gyrosa. After several 
of the tests the flasks were kept at room temperature for some days. 
Tt was found that all developed normally except those which had 
been kept at 40° and 37.5° C. These developed more slowly than 
those which had been kept at lower temperatures. It was particu- 
larly noticeable also that £. parasitica and E£. gyrosa developed prac- 
tically as well after being kept at 40° as at 37.5° C., while cultures 
of Z. fluens which had been in 37.5° developed fairly well; but if 
kept at 40° for three days they entirely failed to develop. 
DISTRIBUTION OF THE SPECIES OF ENDOTHIA. 
During the past two years the writers have studied over 600 speci- 
mens of Endothia from various parts of the world. The greater 
number of these specimens have naturally come from the United 
States. The maps (figs. 1-4) show the known ranges of the various 
species in this country. Each dot on a map represents a locality 
from which the species has been collected. Frequently, of course, 
many specimens have come from a single locality; hence the number 
of dots by no means represents the number of collections. 
In the case of E'ndothia parasitica, the dark portion represents 
the area over which the blight is practically continuous; that is, 
practically all the stands of chestnut are either diseased or dead. 
The dots represent known isolated infections and the solid line marks 
the botanical limit of the chestnut. 
Endothia gyrosa is known only from the United States, but has a: 
range in this country wider- than that of any other species. As 
shown in figure 1, it has been found as far north as central Michigan, 
east to Connecticut, on the Pacific coast near San Francisco, and on 
