SOME STUDIES OF THE GERMINATION OF THE SEED OF ORYZA SATIVA. 149 
radicles observed in the seedlings, which remained in the oxygen free air at 
the end of 96 hours, while the radicles reached a length of as much as 10.5 
mm. (average of twenty grains) in the seedlings which were removed from 
the oxygen-free air at the end of 48 hours, exposed to the ordinary air and 
allowed to stay another 48 hours. 
The results are verified by another set of experiments, using hydrogen 
eas for the replacement of air and with lower atmospheric pressure through 
partial removal of the air by means of a suction pump. The development of 
the radicle is dependent on the amount of available oxygen present. If the 
air is partially replaced or removed, the radicle develops only very little, and 
with a complete absence of available oxygen no development of the radicle 
becomes possible. 
The data above given show that the development of the radicle is de- 
pendent on the oxygen supply, whether the grains are submerged in water 
or placed on the moistened filter paper to supply a sufficient amount of 
moisture necessary for germination. As soon as the germinated grains, in 
which the development of the radicle is checked by lack of oxygen, are 
allowed to be accessible to the ordinary air, the radicle begins to develop. 
Many years ago, Kirps (1884, p. 599) gave a biological interpretation 
of the absence of root hairs and the vigorous elongation of shootlets in 
Oryza seedlings. He considered these facts as examples of the adaptation 
of water plants to the environment. We have seen that the development 
of root hairs and the rapid elongation of the rootlets take place if the grains 
are germinated in moist air, instead of in water. ‘The phenomena are simply 
due to the influences of external conditions. Deficiency in the oxygen supply 
in submerged condition is the vital cause of the slowness in the growth of the 
radicle, thus on the removal of this limiting factor the growth commences 
rapidly, as has already been observed. 
IV. The Effect of H and OH Ions on Germination. 
The stimulating action of H and OH ions on the germination of the 
seed in Sagittaria is reported by A. Fischer (1907), but his result is not 
verified by Crocker (1907, ’14). In the germination of the grains of Oryza, 
