On the spore formation process in actinomycetes

* This article was first published in its complete English-language version in Rivista di Patologia Vegetale (now Journal of Plant Pathology), suppl. vol. VII, series IV (1971). We thank Prof. Giovanni Martelli for kindly granting us permission to reprint its first part on this occasion. * * Istituto di Patologia Vegetale, Università di Milano. Abstract. Details of Streptoverticillium structures as detected by scanning electron microscopy are illustrated. The development of species belonging to the genus has been followed from germination to spore production. Sporulating features of pseudoverticillate cultures have also been observed. The peculiar characteristics of spore formation, which includes an initial twisting of the sporulating hypha, are documented.