The changes induced in carbohydrate metab. of P. aurelia by exposure to uv irradn. were investigated. Uv radiation for 5 min caused an increase in carbohydrate levels followed by a fall after longer periods of irradn. The total free sugars per unit of protein decreased initially but then showed a slight increase up to 10 min of irradn. The ratio of arabinose to galactose in the polysaccharide isolated from P. aurelia was not affected by the radiation. Polysaccharide biosynthesis was completely inhibited by irradn. for 5 min, while irradn. for longer periods inhibited glucose incorporation but not that of galactose or arabinose. The sp. activity of amylase at pH 5.2 was substantially increased by irradn. for 10 min, but it returned to normal with time. While protein content was not affected by irradn. for 10 min, 25 min exposure resulted in 60% loss of proteins and was lethal
