90 
Journal of Mycology 
[Vol. 12 
No. 1. 20 
No. 2. 17 
No. 3. 72 
No. 4. 62 
No. 5. 3 
No. 6. 3 
No. 7. 2 
No. 8. 11 
No. 9. 116 
No. 10. 20 
No. 11. 28 
No. 12. 0 
On May 18 the cylindrical brown masses of teleutospores 
were found arising from many of the uredo sori. The surround¬ 
ing uninoculated leaves on the same tree showed at this time an 
occasional uredo sorus, varying from one to three on a few of the 
leaves, but no signs of teleutospores were yet to be found. This 
seemed to indicate that infection Had taken place later in the 
case of the natural inoculations than in the case of the artificial 
ones. 
This experiment, conducted in the open woods where there 
was possibility or perhaps probability of infection from other 
sources is, of course, not conclusive. The large number of sori 
occurring on most of the artificially inoculated leaves as com¬ 
pared with the very small number found on the surrounding 
ones, taken in connection with their much earlier appearance, 
seems however to indicate a genetic relation between these forms. 
Other attempts to produce artificial infection undertaken dur¬ 
ing the middle of the day failed, but later experiments made in 
the evening were apparently successful, as numerous sori of the 
Cronartium developed on the inoculated leaves and few or none 
on those uninoculated. Unfortunately, we have not thus far had 
opportunity to carry out artificial inoculation experiments under 
conditions which would preclude the possibility of infection from 
•any other source. 
As bearing upon the probability of the genetic relation of 
these two forms, additional evidence is furnished by the follow¬ 
ing observations: On May 17, 1903, a small tree of Finns Vir- 
giniana, about five feet high, was found having a large spore¬ 
bearing excrescence of Peridermiinn cerebrum on its trunk about 
one foot from the ground. About two feet away two seedling 
oaks were growing, one Quercus Marylcmdica and the other Q. 
Prinus, bearing about a dozen leaves each. Most of the leaves on 
both of these plants had their under surfaces almost literally cov¬ 
ered with the uredo sori of Cronartium Quercuum, and many 
showed teleutospores forming. We have been unable to find any 
record of the fungus occurring on Q. Prinus and have never found 
it ourselves except in this instance, in spite of diligent search in 
various localities where the Peridermium is found, but not in such 
