ENDOTHIA PARASITICA AND RELATED SPECIES. 45 



placed on a window sill were opened and examined. In spite of the 

 cold weather prevailing during this test and the consequent low tem- 

 perature of the room at night, these plates contained an average of 

 nearly 200 well-developed spore masses. 



At the end of 35 days the chestnut-twig agar plates which had 

 been kept in the light showed an average of 160 spore masses, while 

 those kept in darkness showed an average of 130 spore pustules, a 

 comparatively small difference in favor of the light plates. There 

 was, however, a wide difference between the various plates in each 

 series, and it was impossible in most cases to distinguish cultures 

 grown in the light from those grown in darkness either by the num- 

 ber, size, or arrangement of the pycnidia and spore masses. 



From these experiments it is evident that pycnidia are produced 

 abundantly in total darkness on chestnut-twig agar as well as on 

 other favorable media. There is no perceptible difference in the 

 amount of spore production or in the arrangement of pycnidia be- 

 tween cultures kept in total darkness and those kept in the light 

 during the day if the temperature and evaporation remain the same 

 in both. Continued observation of numerous cultures grown both 

 in daylight and in darkness has convinced the writers that light has 

 no perceptible effect on mycelial growth either in amount, nature, or 

 color production. It seems evident, therefore, that light is a neg- 

 ligible factor in the growth and fructification of these fungi. 



TEMPERATURE RELATIONS. 



In an earlier paper (77, p. 9) the writers published the results of 

 three series of tests made to determine the temperature relations of 

 three species of Endothia. Since the publication of that paper cul- 

 tures of other species and additional material of some of the species 

 from widely separated localities have been secured. Four series of 

 temperature tests including this new material were made on solid 

 media. 



TESTS ON SOLID MEDIA. 



In these tests cultures of Endothia. gyrosa, E. singularis, E. fluens, 

 E. fluens mississippiensis, and E. parasitica were tried on corn-meal 

 agar in slanted tubes, oatmeal in flasks, and potato agar in slanted 

 tubes. The cultures tested were from specimens chosen from the 

 extremes of the known ranges of the fungi and from their different 

 hosts. No difference could be detected in the various cultures of the 

 same species, even in those from widely separated localities and from 

 different hosts. Cultures appeared to have the same temperature 

 relations whether made from spores or mycelium. The results may 

 be briefly summarized as follows: 



At 41° and 39° C. there was no growth in any species. Cultures removed 

 from the incubator at the end of 11 days and kept at room temperature showed 

 no growth. 



