DAMPING-OFF IX FOREST NTJESERLES. 61 
A species of Phytophthora was isolated by Mr. E. G. Pierce from 
damped-off Pinus resinosa in Minnesota and used in four inocula- 
tion experiments, the results of which appear in Table VIII. In the 
first of these experiments unboiled water was used on the pots, and 
mice obtained access to the pots of the second test. Probably as a 
result of these things infection occurred in the controls in both cases, 
and the results were inconclusive ; in the later experiments these 
two sources of infection were eliminated, and in experiments 68 and 
72B the controls were free from disease. Parasitic activity was in- 
dicated rather strongly in experiments 68 and 72 (on P. resinosa and 
P. banksiana) and to a certain extent in experiment 66. In experi- 
ment 67 it was evident that the Phytophthora was nearly or entirely 
inactive. Comparison of the results in experiments 66 and 68 with 
the results from inoculations with Rheosporangium aphanidermatus 
in the same experiments (Table VII) suggests that the Phytoph- 
thora may be better able to attack the pine from which it was isolated 
than the Eheosporangium, while the latter fungus caused consider- 
ably more destruction to Pinus banksiana than the Phytophthora. 
Comparison of the results in the pots inoculated with Phytophthora 
and those inoculated with Pythium debaryanum in all the experi- 
ments indicates that the Phytophthora strains used were less virulent 
than most of the strains of P. debaryanum and very certainty less 
destructive than the most active strains of either P. debaryanum or 
Corticium vagum. This species of Phytophthora has been reisolated 
from damped-off Pinus ponderosa in experiment 72. 
Direct inoculations of the stems of seedlings of Pinus resinosa soon 
after they emerge from the soil have so far confirmed the lack of 
parasitism of Phytophthora cactorum and of the cultures of Phy- 
tophthora sp. grown by the writer. The identity of this species has 
not yet been determined. It is able to grow only about one- fourth as 
rapidly as Pythium debaryanum on the medium which has been 
used for isolation and may therefore be more common in the seed 
•beds than the small number of isolations by the planted-plate method 
would indicate. However, its oospores, larger and darker than those 
of Pythium debam/anum (usually over 20 jjt, in diameter), should have 
been recognized in the routine microscopic examination of planted- 
plate cultures had this species been frequently present, even if it 
had not grown fast enough to get out ahead of the other organism 
and allow isolation. It is not believed that it is common enough in 
pine seed beds to be of importance, even if other strains should be 
found more virulent than those which have been available. 
MISCELLANEOUS PHYCOMYCETES. 
A fungus, apparently referable to the somewhat indefinite Pythium 
artotrogus (Mont.) De Bary, was isolated by Mr. Glenn G. Hahn 
from Pinus resinosa in Michigan and from damped-off Pinus bank- 
