De Bary published his first work on fungi in 1861, and then spent more than 15 years studying Peronosporeae, particularly "Phytophthora infestans" (formerly "Peronospora infestans") and "Cystopus" ("Albugo"), parasites of potato. In his published work in 1863 entitled "Recherches sur le developpement de quelques champignons parasites", he reported having inoculated spores of "P. infestans" on healthy potato leaves and observed the penetration of the leaf and the subsequent growth of the mycelium that affected the tissue, the formation of conidia, and the appearance of the characteristic black spots of the potato blight. He also did similar experiments on potato stalks and tubers. He watched conidia in the soil and their infection of the tubers, observing that mycelium could survive the cold winter in the tubers. From all these studies, he concluded that organisms could not be generated spontaneously.