A SCLEROTIOID DISEASE OF BEECH ROOTS. 67 
Mébius,* and others agree that the only effect which the 
fungus has on the root is to stunt it, and as if to counter- 
balance this, it causes it to branch more frequently than it 
otherwise would. A multi-branched coralloid form of root 
is thus brought about. This has been one of the reasons 
for considering the relation of fungus and root a symbiotic 
one, for in cases of parasitism some form of hypertrophy, 
starch accumulation, or other evidence of stimulus is met 
with. In the tubercles described there is evidently some 
form of stimulus which brings about the proliferation 
of roots, and that stimulus is probably exerted by the 
fungus mycelium. To that extent the phenomenon would 
lead one to class the structures among such as are 
formed because of the action of some parasitic fungus. 
But there is here no evidence of parasitism, no starch ac- 
cumulation, and what is more, no evident connection between 
the fungus and the root. The hyphae simply surround the 
roots without entering the cells. Because of the greatly 
increased and abnormal growth of the roots, which cannot 
be without effect on their physiological activity, much less 
of benefit to them, one must class the tubercles as patholo- 
gical conditions of these roots. The presence of a large 
number of small sclerotia together with the tubercles sug- 
gests that the sterile mycelium of the tubercles probably 
belongs to some Hymenomycete which usually forms sclero- 
tia. Some of these hyphae come into contact with the 
beech roots, stimulate them, and then, in their further 
growth, adhere to the sclerotium-forming tendency and thus 
bring about the tubercles described. Their nearly constant 
form and size, as well as the similarity of the loose hyphal 
network with that of the small sclerotia all point in that 
direction. 
The formation of numerous twisted roots with short 
* Mobius, M. Der Erdboden in Beziehung zur Ernihrung der Pflanzen, 
(Gartenwelt $:154. fig. 7. 1898.) 
¢ Frank, B. Ber. d, deutsch. bot. Gesell. $: 258. 1885. 
