130 BROOKLYN BOTANIC GARDEN MEMOIRS 



of which are inhibited in their growth, lacking bordered pits and 

 having thin walls, that is, are more in the nature of parenchyma. 

 Wornle was especially fortunate in having the opportunity for con- 

 sultation with Hartig and Tubeuf in his work, but he was handicapped 

 in studying American species by being restricted to a limited number 

 of dried specimens. He agrees in the main with Farlow's account of 

 the location of the mycelium in G. hiseptatum and G. Ellisii, although 

 he makes no mention of Farlow's work. He concludes further that 

 the mycelium of G. hiseptatum is intercellular and is entirely absent in 

 the wood. The tracheids are somewhat irregular and have thinner 

 walls than ordinarily. He found that the hyphae of G. Ellisii are 

 about 8 ;u in diameter and are present in the wood, bast and cortex. 

 The brown hyphae are associated with brownish cells which together 

 make easily recognizable patches. The mycelium here also is strictly 

 intercellular. His study of a three year old stem of red cedar infected 

 with G. clavipes disclosed the fact that the tissues of the host are only 

 slightly affected. The mycelium is distributed not only beneath the 

 sorus but in the whole periphery of the twig, especially in the bast 

 region. The wood is entirely free from the fungus. Wornle pre- 

 dicted that this rust must develop sori one year after inoculation 

 because in this three-year-old stem he found traces of two former 

 sori, one above the other. 



Harshberger's accounf* of the relationships of hyphae and 

 host cells deserves special consideration, inasmuch as it does not 

 agree in certain important particulars with the statements made by 

 Farlow and Wornle. He finds that in G. hiseptatum the mycelium 

 is quite generally present in the wood region where he states the 

 hyphae are for the most part strictly intracellular. They run down 

 through the lumen of a tracheid, pass out through bordered pits, 

 enter an adjacent tracheid, or move over to medullary ray cells which 

 they penetrate and thus become established where they receive nour- 

 ishment sufificient to maintain their perennial growth as the wood of 

 the burl increases in diameter. He believes that the hypha actually 

 in the lumen of the cambium cell is responsible for the stimulation of 

 this cell to produce abnormal amounts of wood! He describes and 

 figures these intracellular hyphae in much detail, especially the 

 hyphae in longitudinal sections of wood. The explanations accom- 

 panying his figures leave no doubt of Harshberger's opinion regarding 

 the identification and location of intracellular hyphae. He lays much 

 stress on the presence of "plugged" tracheids. He believes that 

 they are caused by the mycelium with which they are generally asso- 



* Harshberger, J. W. Two Fungous Diseases of the White Cedar. Proc. Acad. 

 Nat. Sci. Philadelphia 1902: 461-504. pi. 22, 23. 



