STUDIES OF GLOMERELLA FROM DIFFERENT HOSTS. 37 



CULTURES. 



On October 16 plates were poured, using conidia from a leaf in the 

 moist chamber. On October 24 many dark acervuli were present, 

 the color being due in part to the dark basal hyphae and in 'part to 

 the brown setae. On November 6 many mature perithecia were also 

 found in the plates. Subcultures made by transfer of conidia from 

 these plates also developed perithecia. Several other cultures made 

 from the same material produced both acervuli with setae and mature 

 perithecia with ascospores. In some of the cultures the perithecial 

 form predominated. 



In order to study the behavior of the fungus with reference to its 

 variability in different generations under practically the same con- 

 ditions, a pure line or strain was isolated by taking single conidia 

 from a plate which had also produced ascospores. These were trans- 

 ferred to tubes of corn-meal agar. The plates from which they were 

 taken finally developed acervuli with setse; also some perithecia. 

 Only one of the tubes containing a single conidium gave a pure 

 culture; the others became contaminated. This one produced several 

 rather definite areas of mature perithecia and a few acervuli bearing 

 pinkish masses of conidia. The second generation was obtained by 

 transfers of conidia from this tube to two others. One of these tubes 

 produced an abundance of perithecia, while the other contained 

 fewer perithecia and a greater development of mycelium. Conidia 

 were present in both, but were few and did not form in large, distinct 

 acervuli. These cultures had the same general appearance as the 

 first generations from ascospores described below. 



On October 18 pure-line cultures were started, using a single 

 ascospore from a poured plate made from ascospores derived from 

 the original twigs. This culture developed a rather scanty growth 

 of light-colored mycelium with but few conidia. Later, a few peri- 

 thecia were found, but asci had not developed. The culture became 

 contaminated with bacteria and was discarded. 



One tube, to which a whole ascus had been transferred, produced a 

 few inconspicuous acervuli with setae and later an abundance of peri- 

 thecia with mature asci and spores. Transfers were made from this 

 tube, producing the second ascospore generation. A few conidia 

 developed but no distinct acervuli. Mature perithecia and ascospores 

 were also formed. The perithecia were not evenly distributed, as 

 was sometimes the case in other cultures, especially those from the 

 form on Persea gratissima. 



Generation 3 was started by transfer of perithecia from generation 2. 

 This culture produced an abundance of perithecia and a few conidia 

 without acervuli. The appearance of the cultures was very similar 

 to that of generation 2. 



252 



