Abstract
1. The rice seeds or kernels internally infected by Piricularia Oryzae Br. et Cav. or Ophiobolus Miyabeanus Ito et Kuribayashi (Helminthosporium Oryzae Breda de Haan) show generally a visible discoloration which varies froma small spot or a streak to a large area involving the entire surface, sometimes a shriveling.
2. Absence of external signs of disease can not be recognized as the conclusive evidence for the fact that the seeds are quite free from internal infection, because the writer has proved the existence of some internal fungous parasites of the rice seeds of healthy appearance by means of the microscopical examination as well as the isolating experiment.
3. The salt water selection (1. 1 sp. gr.), a method of selection by means of soaking seeds in a salt solution, seems to be unapplicable to the selection of healthy rice-seeds.
4. According to the results of inoculation experiments, Piricularia Oryzae and Ophiobolus Miyabeanus seem to have a power to infect the seeds at any time before and after the flowering period of rice.
5. Some parasitic fungi internal of rice seeds, such as Piricularia Oryzae and Ophiobolus Miyabeanus, cause the first occurrence of diseases in the spring, infecting the young seedlings soon after germination.
6. Piricularia Oryzae hibernating in rice seeds may not lose its vitalityat least for two years, and Ophiobolus Miyabeanus for four years under the same condition.
7. Piricularia Oryzae internal of rice seeds loses its vitality after five minutes in hot water kept at 50°C., while Ophiobolus Miyabeanus at 55°C under the same condition.
