8 CIRCULAR NO. 131, BUREAU OF PLANT INDUSTRY, 



only a slight amount of growth in a few tubes. E. gyrosa showed 

 about the same amount of growth as E. parasitica, but the growth was 

 decidedly more normal in apj^earance. Only two of the tubes of E. 

 radicalis which had shown no growth at 35° C. began to grow when 

 kept at room temperature. 



In one week at room temperature, 22° to 24° C, Endothia j^arasitica 

 and E. gyrosa nearly, if not quite, covered the surface of the medium, 

 while E. radicalis showed but little less growth. In 14 days all 

 species at room temperature completely covered the surface of the 

 medium with a typical mycelium. This appears to be at least nearer 

 the optimum temperature than any other used. 



At 18° C. growth in all species was much less than at room tempera- 

 ture. There was, however, a marked and typical difference between 

 Endothia 'parasitica and E. radicalis, which was more pronounced 

 than is usually the case at room temperature. The differences were 

 practically the same as those described for potato-agar cultures on 

 page 11. 



At 16° C. the cultures differed very little from those at 18° C. 



At 7° C. there was no growth whatever. 



Series 2 {six tubes of each) on potato agar -\-6. — At the end of 15 

 days cultures at 40° C. showed no growth. 



At 35° C. Endothia parasitica showed a slight abnormal growth, as 

 described in series 1. E. radicalis showed no growth whatever. E. 

 gyrosa showed slightly more than E. parasitica and was decidedly 

 more normal in appearance. Transferred to room temperature about 

 half of the E. radicalis cultures grew. 



Series 3 on corn-meal and potato agars. — In this test there was no 

 noticeable difference in the behavior of the fungi on these two media. 

 Cultures from over 70 different specimens chosen from the extremes 

 of the known ranges of the several species and from near the center 

 were used. These cultures were made partly from spores and partly 

 from mycelium. In no case was any difference noted in the cultures 

 of the same species from the various localities or different inoculating 

 material. At the end of 24 days there was no growth in any at 40° C. 



At 35° C. Endothia 2^(irasitica showed an abnormal growth, as 

 described for series 1. Material from New Hampshire and from 

 Virginia showed no difference. E. radicalis showed no growth. 

 E. gyrosa showed growth about equal to that of E. jmrasitica. Cul- 

 tures from Michigan and Alabama showed no difference in the amount 

 of growth. 



At 32° C. Endothia parasitica produced a fairly abundant growth, 

 which had taken on the characteristic orange color. E. radicalis 

 showed but a slight amount of growth. E. gyrosa showed a little 

 more development than E. parasitica. 



ICir. 131] 



