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. biseptatum and G. Ellisit, although 
he makes no mention of Farlow’s work. He concludes further that 
the mycelium of G. biseptatum 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. Ellisti are 
about 8 w 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. Wo6rnle 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 account* 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. biseptatum 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 sufficient 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- 
4 Harshberger, J. W. Two Fungous Diseases of the White Cedar. Proc. Acad. 
Nat. Sci. Philadelphia 1902: 461-504. pl. 22, 23. 
