PEACH SCAB AND ITS CONTROL. 37 
could be seen to sway, but the spores remained in place. When a drop of water was 
brought in contact with the spores, however, they quickly became detached. 
Experiment 4- — An abundantly sporulating culture on a section of a steamed bean 
pod was placed in a glass tube, 2 cm. in diameter and 30 cm. long, about 2 cm. from the 
distal end. in such fashion that no part of the colony touched the glass. A glass slide 
smeared with glycerin was placed about 1 cm. from the opening of the distal end of 
the tube in position to catch particles which might be blown through. For about 30 
seconds a strong current of air was aspirated into the proximal end of the tube by 
means of a hand bellows. While no attempt was made to measure the velocity of the 
air current, it was strong enough to move the section of wet bean pod several milli- 
meters. It was thought to be at least the equivalent of the strongest wind ordinarily 
affecting an orchard . Subsequent careful microscopic examination of the slide showed 
that only occasional spores were present. In most of these cases the conidiophores, 
rather than the spores, had been detached. 
Experiment 5. — The culture used in the preceding experiment was gently sprayed 
with distilled water by means of an atomizer, in such fashion that only the finest par- 
ticles of spray fell upon it. When a drop of water accumulated at the bottom of the 
pod it was examined microscopically and found to contain myriads of conidia. 
Experiments 6 andl. — Experiments 4 and 5 were repeated, with confirmatory results. 
Experiment 8. — On April 23, 1915, a peach twig about 10 cm. long, similar to those 
used in experiment 2 and bearing more than 30 abundantly sporulating scab lesions, 
was clamped about the base by a cork which was inserted in a bottle of water. Thus, 
the twig was kept fresh and turgid, with about 7 cm. of its length exposed. In this 
condition it was placed out of doors in a brisk wind for two hours. A glass slide 
smeared with glycerin was placed 1 cm. away from the twig upon the leeward side, 
in position to catch spores which might be blown off. At the end of the experiment 
a careful microscopic examination of the slide revealed only occasional spores of 
Cladosporium carpophilum . 
Experiment 9. — The twig used in the preceding experiment was placed in the aspi- 
rating apparatus employed in experiment 4, in such position that it did not touch the 
surface of the tube. The aspirator was operated as in experiment 4. Only occasional 
spores could be found upon the glycerined slide, though they were slightly more 
abundant than in the preceding test. 
Experiment 10. — The twig used in the preceding test was sprayed in the manner 
described in experiment 5. The drops of water which accumulated contained myri- 
ads of conidia. 
Experiment 11. — The twig used in the preceding test was allowed to dry over night 
in the laboratory. The next day it was put in the aspirating apparatus and treated as 
in experiment 9. The results were not materially different from those of experiment 
9, though the number of conidia caught was very slightly increased. 
Experiments 12 to 15. — Experiments 8 to 11 were repeated, with confirmatory results. 
The results of these and of other similar experiments show: (1) 
That the dry conidia of Cladosporium carpophilum are not normally 
abscised or abjected; (2) that in a dry or humid atmosphere they 
remain persistently attached to the parent fungus; (3) that in con- 
tact with water they promptly become detached: (4) that even after 
spores have been detached by wetting the twigs they are not readily 
disseminated by wind after a period of drying. Thus, the evidence 
strongly indicates that under orchard conditions wind may be ex- 
pected to play only a minor role in the dissemination of conidia, while 
