MICHIGAN ACADEMY OF SCIENCE. 
49 
thickly clustered about the roots of the Black Oak. Upon the rootlets and 
connected with the mycelium were numerous ectotrophic mycorhiza struc- 
tures. 
There is little doubt that the three fungi with colored mycelia form mycor- 
hiza with oak roots. Since, however, the mycelium of Russula emetica is 
white and very fine, and since the mycelia of nearly all fungi are white, 
there might be some question as to whether the mycorhiza was caused by 
the Russula or by some other fungus. As other agarics are now known to 
cause mycorhiza, it is quite possible that Russulas also may be mycorhiza 
producers. The mycelium of Russula emetica was so generally associated 
with the mycorhiza structures upon Red Oak roots that it is altogether prob- 
able that it may produce mycorhiza upon the Red Oak, at least, Many spo- 
rophores of several different Russulas were dug up. In no instance, how- 
ever, was there any evidence that they were mycorhiza producers. It would 
be a remarkable coincidence if the mycorhiza of the Red Oak happened to 
be near sporophores of Russula emetica while scarcely any mycorhiza could 
be found near the sporophores of other species. 
The occurrence of sclerotia in connection with Boletus speciosus Frost 
deserves notice, for up to the present time, no one seems to have reported 
a Boletus with sclerotia nor sclerotia connected with mycorhiza. 
In conclusion it can be said that another Cortinarius and probably some 
forms of Russula emetica may produce mycorhiza upon the Red Oak, and 
that Boletus speciosus Frost and Tricholoma transmutans Pk. may produce 
mycorhiza upon the Black Oak. 
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