Abstract
We have already discussed the presence and functioning of a interferon system in primary cultures of tortoise kidney cells and described some physico-chemical properties of the induced interferon elsewhere (Galabov, Savov & Vassileva, 1973; Galabov, Petrunova & Savov, 1973; Galabov & Savov, 1973). In order to more completely characterize the interferon producing system in such poikilothermic vertebrates, a study was carried out using tortoise (Testudo graeca) peritoneal cells.