408 
Journal of Agricultural Research 
Vol. II, No. 6 
somewhat, but the following were found to give the most satisfactory 
results: 
i c. c. from second flask to each of 2 Petri dishes. 
10 drops from second flask to each of 4 Petri dishes. 
5 drops from second flask to each of 4 or 6 Petri dishes. 
1 drop from second flask to each of 4 Petri dishes. 
In this way the number of plates per bird ranged from 12 to 20 in all 
cases, except bird No. 1. The number of drops delivered per cubic centi¬ 
meter by the pipette were counted each time and were found to be fairly 
constant for any single pipette, although they varied from 24 to 53 drops 
for the different ones used. A tube of melted 3 per cent dextrose agar 
plus 10, which had been previously cooled to from 42 to 45 0 C., was added 
to each Petri dish and the plates rotated, so as to secure a uniform dis¬ 
tribution of the spores. The entire operation of scrubbing and plating 
was carried out in a culture room, with every precaution against contami¬ 
nation from any source. 
The plates were incubated in an inverted position in the laboratory and 
an attempt was made to keep the temperature of the room as nearly as 
possible at 25 0 C. At the end of four days those colonies suspected of 
being the chestnut-blight fungus were marked with india ink (3). Two 
or three days later this diagnosis was verified, and all doubtful colonies 
were transferred to other agar plates, to make certain of their identity. 
A count was also made of the number of bacterial and yeast colonies, of 
the number of fungous colonies other than those of Endothia parasitica , 
and of the number of species of fungi represented, as nearly as could be 
determined from cultural characteristics. With this information and 
knowing the calibration of the pipette used, it was an easy matter to com¬ 
pute the total number of viable spores or bacteria carried by each bird. 
The original wash water was poured back into the flask and several 
cubic centimeters of formalin added to inhibit the growth of the spores. 
At a later time the wash water of those birds yielding positive results 
was centrifuged in 10 c. c. quantities, the sediments thus obtained 
thrown together and centrifuged again, so that the entire sediment was 
concentrated in about 2 c. c. of water. This final sediment was given 
a thorough microscopic examination, primarily for its pycnospore or 
ascospore content of Endothia parasitica and secondarily for the num¬ 
ber and kinds of other fungous spores which it might contain. 
LIST OF BIRDS TESTED 
A detailed record of the place and time of shooting of each bird is 
given below. 
The birds tested belonged to nine different species. (See Table I.) 
One of these, the flicker, gets most of its food from the ground, although, 
as a rule, it flies into a tree when the person approaching is still a good 
distance away. Another species, the junco, gets practically all of its 
