PEACH SCAB AND ITS CONTROL. 19 
The spores were placed in drops of sterile distilled water, meteoric 
water, and nutritive solutions, respectively, on glass slides in moist 
chambers; in liquid and solid media in Van Tieghem cells; and in 
plate cultures of agar infusions. The cultures were incubated under 
various regulated conditions. The glassware was cleaned in the 
standard manner for physiological experiments, and distilled water 
was redistilled from Jena glass. For most purposes, the open drop 
cultures on glass slides in Petri dishes were most convenient and 
satisfactory. 
GERMINATION IN WATER. 
In diffuse light or in darkness, at 18° to 27° C, the first evidences 
of the germination of conidia in sterile distilled water appear, after 
about 8 to 12 hours, as small, highly refractive, hyaline protuberances 
of the inner walls of the spores. These gradually develop into delicate, 
hyaline, septate germ tubes, 2 to 4 n in diameter, which usually 
attain a length of about 10 to 20 ix within 24 hours after the beginning 
of the experiment. Little growth occurs after the second day, when 
the tubes are usually 30 to 60 /* long. They rarely become longer 
than 75 ii unless suitable nutritive material is added. The germ tubes 
may extend from any part of the surface of the spore, but ordinarily 
they are developed at or near the ends. If only one is produced, it is 
generally borne at or near the basal end. Frequently a tube is 
developed from each end, but rarely are more than two produced 
from a single spore in pure water. 
In parallel experiments with sterile distilled water and meteoric 
water no noteworthy differences in results were observed. 
GERMINATION IN NUTRIENT MEDIA. 
In drops of 1 per cent prune or raisin decoction, or a variety of 
other similar nutrient solutions, the early development of germination 
is practically indistinguishable from that in water, the effects of the 
nutrient media being manifested chiefly in the rapidity and vigor 
of development. In such solutions, under the conditions already 
mentioned, early stages of germination may be observed within 
4 to 8 hours. After 12 hours the germ tubes usually measure about 
3 to 4 by 15 to 25 m- Within two days they frequently attain a 
length of 150 to 250 fj, and become considerably thickened, branched, 
and septate. 
In sap expressed from green Elberta peaches germination is practi- 
cally indistinguishable from that in 1 per cent prune decoction. 
In plates of 1 per cent prune agar, or a variety of similar agar 
infusions, germination closely parallels that in drops of prune decoc- 
tion. 
In Van Tieghem cells the spores germinate normally in various 
liquid and solid media. 
