Abstract
The hemolytic activity of the coelomic fluid of Paracentrotus lividus against vertebrate erythrocytes was investigated. It was found that this activity corresponds to a thermo‐labile, calcinum‐dependent protein. The chemico‐physical and biological properties of this protein are compared to those of the counterparts in other echinoderm hemolytic systems. No immunological cross‐reaction could be demonstrated between P. lividus and Holothuria polii hemolysin.