416 Journal of Agricultural Research Vol. II, No. 6 
MICROSCOPIC EXAMINATION OF CENTRIFUGED SEDIMENTS 
The sediments from those birds yielding positive results were given a 
thorough microscopic examination, primarily to ascertain whether the 
birds were carrying pycnospores or ascospores. (See Table IV.) Asco- 
spores were not found to be present in a single instance. However, in 
sediments from birds yielding high positive results pycnospores could be 
found very easily. Where the positive results were not so high, pycno- 
spores were located with more difficulty, but could be found in all sedi- 
ments except those from birds showing by cultures the smallest number 
of spores of the blight fungus. The results from cultures substantiate 
the microscopic examinations, since the rate of development of colonies 
of the chestnut-blight fungus always indicated their origin from pycno- 
spores (3). 
TABLE 1V.—Results of microscopic examination of centrifuged sediments of birds Nos. 
I to 36 
Number Number 
lof sporesof lof sporesof| 
Endothia Endothia 
Bird |parasitica) Kind of spores shown by micro- Bird parasitica] Kind of spores shown by micro- 
No. | carried, scopic examination. No. carried, copic examination. 
as shown * las shown 
by cul- by cul- 
tures. tures. 
Ths o | Examination not necessary. 20,2... o | Examination not necessary. 
2.. ° Do. BU asec 5,780 | No ascospores. 
Bin ° Do. C D2 vicars 7) 502 Do. 
Ae 10,000 | No ascospores. 23....{ 254,019 | No ascospores; pycnospores fairly 
Bios 30,000 | No ascospores; pycnospores pres- abundant. 
ent. Cy Ey o | Examination not necessary. 
6... 731333 Do. BG ds 27,108 | No ascospores; pycnospores pres- 
tr 109, 022 Do. ent. 
Bix 92,000 Do. _ 26.... 59, 742 Do. 
9... o | Examination not necessary. 27....| 624,341 | No ascospores; pycnospores fairly 
Io... 757,074 | Noascospores; pycnospores abun- abundant. 
dant. o | Examination not necessary. 
TE 15,625 | No ascospores; pycnospores pres- ° Do. 
ent. ° Do. 
31, III Do. ° Do. 
25,000 Do. | ° Do. 
° zecoinee not necessary. 36,312 | No ascospores; pycnospores pres- 
° 0. ent. 
° Do. SA caine o | Examination not necessary. 
6,566 | No ascospores. 35.65 ° Do. 
5,000 Do. 36.... ° Do. 
5,655 Do. 
During the time covered by our analyses there were five periods during 
which ascospores were expelled in the field—i. e., on March 20 and 21, 26 
and 27, April 4 and 5, 13 to 16, 27 to 29. On these days ascospores were 
ejected at both Martic Forge and West Chester, but only a very few spores 
were expelled on March 20 and 21 and on April4and5. If the remaining 
dates are compared with Table III, it will be noticed that the birds yield- 
ing the highest positive results were shot just after the rains which pro- 
duced copious expulsion of ascospores. It might therefore be expected 
that birds would be carrying these spores as well as pycnospores, but such 
does not appear to have been the case. Studies on wind dissemination 
show that ascospores are carried away by the wind upon being shot out 
