On the Heatresistance of Cl. welchii

On the heat resistance of Cl. welchii isolated from the human faeces and the soil, the following experimental results have been obtained.(1) About 60-80% of Cl welchii isolated from the faeces is resistant to the heat treatment of 100°C for 1 hour.(2) The resistance of Cl. welchii isolated from the farm soil dressed with the faeces varies according to the number of years passed after dressing. Within one year, about 80-100% Cl. welchii was resistant to the heat condition mentioned in, while the percentage decreased to 10-30% in several years. After 10 years, just like in the case of non dressed soil, resistant Cl. welchii was hardly detected from the dressed soil, though about 30-80% it was resistant to 80°C for 10 minutes.(3) When the soil sterilized under the 120°C for 20 minutes was mixed with the faeces and kept about one year at the room temperature, the limit of the resistance of Cl. welchii decreased, in about oneyear, to 80°C for 10 minutes -100°C for 20 minutes.(4) The colony of Cl. welchii turn green in 3 hours at 37°C with the supply of oxygen, but it never turn green at the temperatures below 10°C.