SUMMARY1.The ascocarp ofAscobolus magnificusoriginates from a pair of morphologically distinct primordial—a large ascogonium the end of which functions as a trichogyne, and a club-shaped antheridium.2.Papulospora magnificaHotson is an asexual stage ofAscobolus magnificusDodge.3.The intrahyphal mycelium, found in old cultures is simply a case of“Durchwachsungen,”or“cordon interne.”4.The strains here reported, which were obtained from germinated papulospores or ascospores, were self-sterile in the experiments conducted, but always produced papulospores.5.Sexual reproduction occurs in cultures containing two strains properly chosen.