48 BULLETIN 380_, U. S. DEPARTMENT OF AGRICULTUBE. 



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 30° 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 Endothia fiuens is less resistant to the higher 

 temperatures than either E. parasitica or E. gyrosa. After several 

 of the tests the flasks were kept at room temperature for some days. 

 It 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 E. parasitica and E. gyrosa developed prac- 

 tically as well after being kept at 40° as at 37.5° C, while cultures 

 of E. -fluens which had been in 37.5° developed fairly well; but if 

 kept at 40° for three daj^s 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 gi'eater 

 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 Endothia 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 



