53 



(JROWTII (»\ (»'IMIi:ii MATKUIALS 'I'llAN ( If KSTXUT. 



Ill llic lalMtiMlorv (lie Jiiiigii.s gi'ow.s well on ;i \;iii('iv ol' arlili- 

 cial media, pcrliaps jiiosL readily on potato aL;ai' I hat lias been 

 made .slighll}' aeid. .Material was submitted to us of white oak 

 and blaek oak bark, collected by Mr. .J. K. Guyer, agent of the 

 I'eiiusylvaiiia ( 'oiiimission, which bark had been kiib-d by lii*- [trc- 

 vlous to its observation, and sii;>\,c piisinh's (d' what seemed to 

 be Diaixnilic ixinisitku. (,'areful microscopic examination siiow- 

 ed that the moridiological features corres|»oii(h'd (doseiy to those 

 of l>\n porllic jxiid.sitict!, as did also the gro\\tli of the fungous in 

 artilicial culture, lied oak twigs killed by steaming in the process 

 of stei'ilization, were readily infected by Duiporihc pant. •silica ob- 

 lained from a ty]>ical chestnut lesion. While it is desiralile to 

 carry on rnilhcr cross iiiocnlalion ('X[)t'ri incuts, it seems rea- 

 sonable to sup[)ose, in the light of present evidence, that hUipor- 

 tlic p(ira.sitiv(( may, under unusual circtimstances, estaldish itself 

 saprophytically on portions of trees outside the genus Vaatanea, 

 if these portions are already dead. >Ve have found no evidence 

 that the fungus produces in any sense a disease of siicii trees as 

 the oak. 



RELATION TO J.KillT.XI \( J IX.TIRY. 



Ill August, 11)08, .Mr. (Jeiu-ge W'wi, of the i*ennsylvania Tor- 

 estry Department, directed the attention of the speaker to a 

 cliestnnt tree in an juivaiiced stage of infection, that had been 

 struck by lightning earlier in the season, when its leaves were 

 half grown. AVliere the wood had been splintered along the 

 lightning track, there were numerous p^cnidia standing apart 

 one from the other, as is characteristic of Diaporthc ptirasitica 

 when fruiting on wockI rather tiiaii on bark. .Alany of these fruit- 

 Itodies were deep in the cracks made by the lightning, and evi- 

 dently had lieen formed after the stroke. Si»ecimens taken from 

 the wood and Ircuii tiic bark near by, \\li('n tested, gave good 

 germination of spoi-es. Probably the bark inrectiiui, A\liicli 

 seemed to dale far back, existed at tlic t iiiic of t he stroke, and the 

 fungus spread I'l-oiii this to the sliatlcre(l wood, ijic lightning 

 presumabl^\ not having killed the fungus in the vicinity. 



