48 
TENTH REPORT. 
emetica growing in the soil. The mycelium of this fungus also was in every 
instance associated with the mycorhiza structures of Red Oak roots. 
Some of the mycorhiza structures from Red Oak rootlets were imbedded 
in paraffine and sectioned. When cut thin and stained with gentian- violet, 
they present almost exactly the same appearance as those figured bv Noack. 
The rootlet is surrounded as by a felt of mycelium, whose fine strands extend 
as a network down between the outer palisade-like cells. 
After making these discoveries we paid more attention to mycorhiza, both 
to confirm our first observations and to determine whether other species 
form mycorhiza. Although mycorhiza structures were frequently found 
near the sporophores of various species, it cannot be said with any degree 
of certainty that there was any connection. It is very difficult to follow 
fine white my celia through the soil, and since many kinds of mycelia may 
be found in close proximity, it is easy to mistake one for another. Special 
attention was paid to the Russula emetica which is found in swamps, but it 
is not yet determined whether this form is a mycorhiza producer or not. 
When, however, the fungus mycelium is colored the problem is not so difficult. 
Among the numerous specimens which were collected in a small oak- 
hickory grove within the city limits, was a handsome Boletus, which we 
identified as Boletus speciosus Frost. The stem of this Boletus is of a bright 
yellow color within, a fact which suggested that its mycelium might be yellow 
also. Accordingly I returned to the place where the specimens were col- 
lected, and found some more of the same kind. As soon as I dug into the 
ground, after removing the sporophore, I found the bright yellow mycelium 
running through the soil in all directions and extending down to the subsoil. 
Some of the mycelial strands, which resembled rhizomorphs, were as much 
as a millimeter in diameter. Some of them were within dead roots whose 
cortex alone was still intact, and some followed the course of live roots and 
sent out branches, which were plainly connected with mycorhiza structures 
upon the rootlets. The fungus thus appears to be both a saprophyte and a 
symbiont, if we allow that mycorhiza form a symbiotic relationship. The 
mycorhiza structures in this instance were yellow corresponding to the yellow 
mycelium. Nine sporophores of this Boletus were found within an area 
having a diameter of about three rods. For every one, the yellow mycelial 
strands were found associated with the same kind of mycorhiza structures 
upon the same kind of roots. In October when we returned to follow up 
some of the roots in order to determine to what tree they belonged, we found 
more of the mycelial strands connected with mycorhiza structures upon the 
rootlets. Some of these strands were also connected with small yellow 
sclerotia down near the subsoil. These sclerotia were from one to three 
millimeters in diameter and sometimes as much as eight millimeters long. 
Cross sections of the larger specimens show practically the same cellular 
like structure as those figured by DeBary (5) and Leveille (6). The smaller 
and younger specimens appear to be composed of a dense mass of interwoven 
hyphae very similar to those which are described and figured by Brefeld (7) 
for Coprinus stercorarius Fr. 
On October 2, Dr. Kauffman found a Cortinarius (species not yet deter- 
mined) with a yellow mycelium, which was connected with the mycorhiza 
of Red Oak roots. 
The last fungus that we found producing mycorhiza was T richoloma trans- 
mutans Pk. When some of the sporophores were dug up, younger stages 
were found just beneath the surface of the soil, all growing from a light 
yellow mycelium. The mycelial threads were very abundant and always 
