CHESTNUT BLIGHT FUNGUS 
167 
than under the artificial conditions referred to, where practically no 
mucilage was left on the spores. 
In this connection it might be stated that disease organisms have 
been found to resist desiccation on the seed of the host plant longer 
than on other material. Such is the case with the bacteria causing 
the black rot of cabbage (2). Spores of Glomerella gossypii, the 
cause of cotton anthracnose, retain their vitality much longer when 
dried on cotton seeds than on cover slips (i). Although little evidence 
is at hand to confirm the statement, it is not impossible that spores of 
Endothia parasitica will resist desiccation on chestnut bark much 
longer than on some other materials. 
Practical Bearing of the Results on the Dissemination by 
Birds and Insects 
The conclusion has been reached that birds, and especially migra- 
tory birds (6, 7), are capable of carrying large numbers of viable 
pycnospores of the blight fungus for considerable distances; and that 
insects (9, 10) may be important agents in the local dissemination of 
the blight. Birds were shown to be carrying pycnospores only; the 
same was true of nearly all of the insects from which positive results 
were obtained, although a very small number of ascospores were 
found on several beetles. 
The question of the source of these pycnospores has already been 
touched upon in the introduction. The results herein reported bring 
out the following reasons in support of the belief that these pycnospores 
were obtained in the main, if not wholly, as a result of the brushing 
of birds and insects over diseased and normal chestnut bark: 
1. Viable pycnospores are present in varying numbers on healthy 
bark below lesions after both summer and winter rains. 
2. Large numbers of pycnospores can be obtained immediately 
after a rain, but they may be present in smaller numbers for at least 
two weeks. 
3. The largest numbers of spores were invariably obtained from 
birds and insects frOm about two to four days after a rain, correspond- 
ing rather closely with the. time at which the largest numbers of viable 
pycnospores are present on normal bark below lesions. 
