i9o8] EDCERTON—ANTHRACNOSES 381 



On leaves of Qiiercus velutina also there was found a fungus which 

 does not seem to differ materially from the true Glocosporhim ner- 

 visequum. The disease, which was very common around Ithaca in 

 the summer of 1906, appeared on the leaves in late summer, dead 

 spots being formed 1-2^™ in diameter. The spots were not white, 

 as on the leaves of Q. alba, but brown. Sometimes the disease 

 killed a large portion of the leaf, but generally it appeared merely in 



spots. 



The acervuli were scattered on the under-surface of the dead 

 spots. The spores are somewhat larger than those on the syca- 

 more, being about 1 5-20 X 6-9 /*. This difference seemed at first 

 to separate it from the form on sycamore; but when the two were 

 grown side by side on plates, the difference was not observable. The 

 spores produced in pure cultures at first seemed to be slightly larger 

 than those from the sycamore, but very soon they became the same 

 size (about 9-14X4-6 /u). Only one difference was noticed between 

 the two forms on artificial media. Both forms on bean pods covered 

 the substratum with a grayish to blackish growth and then grew over 

 the Hquid in the bottom of the tubes. On this growth, from the 

 liquid especially, in the culture from Q. velutina there oozed out 

 large drops of golden yellow liquid, which were so abundant that they 

 almost covered the surface. As the culture became older, these drops 

 dried to yellow, waxy crusts. On the form from sycamore no such 

 golden drops were produced. In other ways the two forms were 



indistinguishable on artificial media. 



In the spring on a few twigs there was also found the Myxo- 

 sporium stage. The young twigs were kiUed before the leaves started 

 and were killed back 15-20^- from the end. They were covered 

 with pustules similar to those from Platanus and Q. alba. A 



from 



others. 



to see if the perfect stage would develop. In the spring near the 

 anthracnosed spots were found smaU scattered perithecia, which ^ ere 

 identical with those found on the white oak leaves. The asci ana 



figs 



Tvith the same from 



ascospores 



