A SCLEROTIOID DISEASE OF BEECH ROOTS. 69 
were much contorted, and like those in the tubercles, but 
each rootlet was covered with a sheath of fungus mycelium, 
like that of the typical mycorhiza. It is difficult to say 
whether this mycelium was distinct from that of the my- 
corhiza. I am inclined to think that it was, as it occurred in 
isolated spots, and only among definite clumps of trees, 
while all trees of that locality had the mycorhiza form of 
root. The occurrence of so many forms of mycelia, some 
apparently closely associated with the roots, laying claim 
to symbiotic relationship, others evidently more distinct 
from the root, such as the one which formed the tubercles, 
suggests that the problem of the root fungi in relation to 
trees is still an open one. 
EXPLANATION OF PLATES ILLUSTRATING SCLEROTIOID 
DISEASE OF BEECH ROOTS. 
Plate 55. — 1, Beech root from Grand View, N. Y., showing sclerotioid 
bodies ‘a’ with fungus strands ‘b’ leading from each one (X 3). 2, 
Large tubercle, composed of three smaller ones, whose sheaths have 
united (< 1). The various depressions indicate separate masses of 
roots. A fungus strand comes from each mass, 8, A small sclerotium 
found near the beech roots (< 4). 4, Optical section of early stage of 
tubercle; covered with fungus sheath and showing two branches origi- 
nating close to the root-tip (< 6). 5, An older stage of a tubercle (< 6). 
The fungus sheath has been removed, and the branches are spread 
out. Some of the fungus threads adhere to the roots. 6, Still more 
advanced stage, roots spread out (X 6). 7, a, The beginning of a 
tubercle, ‘s’ fungus strands growing over a root, and spreading out 
forming a sheath (X< 7); b, sheath removed, showing three branches 
just appearing (X 7). 8, Transection of root from tubercle, with a 
portion of the sheath; ‘p’ outer layer of sheath, composed of fungus 
threads of large diameter; ‘s’ inner layer of sheath; ‘e ? epidermis of 
root. 9, Longisection through tip of root, slightly diagrammatic; the 
enveloping fungus hyphae have been omitted ;‘c ? two-layered rootcap;‘e’ 
epidermis; ‘v’ plerome cylinder. 10, A small portion of roots from a 
tubercle. Each branch keeps on growing, and forms branches constantly. 
The line at the side equals 2 millimeters; ‘h’ double layer of fungus. 
hyphae around the root-tip. 
Plate 56. —1, Longisection of a young tubercle, reconstructed from 
