On Sexual Agglutination and Mating‐type Substances (Gamones) in Isogamous Heterothallic Chlamydomonads. I. Evidence of the Identity of the Gamones With the Surface Components Responsible for Sexual Flagellar Contact1

SUMMARY Sexual contact between the isogametes of hetero‐thallic Chlamydomonas species is based on a highly efficient agglutination mechanism, whose complementary components–the mating‐type substances–are localized on the flagellar tips. Evidence is presented that the sex‐ and species‐specific isoagglutinins (gam‐ones) detected in the supernatant of each gamete type are those contact components, secondarily detached in active form. Added to the opposite sex these components can cause agglutination within one gamete type, apparently by the reaction of their combining sites with the complementary receptor groups. The evidence for the identity of the isoagglutinins with the surface substances effecting the normal gamete contact consists of their parallel behavior with regard to the species‐, sex‐, phase‐, and site‐specificity of both reactions.