In the study on the disease of conchocelis, it is necessary to use the thalli of conchocelis which has the same cultural age and the similar physiological condition at a desirable time in any season, because the appearance and development of disease is greatly influenced by the physiological condition which varies with the age of conchocelis.
From the point of view, attempts were made to find the way of getting such conchocelis.
The results obtained are as follows:
1. The leafy thalli of Porphyra okamurai can be kept in living state, at least for half a year when they are stored at -12°C after drying in air.
2. The thalli stored as above mentioned are steeped in sea water for two days, and then cultivate at 22°C under the radiation of continuous light in the enriched sea water, the carpospores are produced and liberated from them. The carpospores germinate into shells and grow as well as the case of the conchocelis obtained naturally.