Some species of the genus Pythium (section Orthosporangium Fisch.) from the soil, with observations on their cultures

1. In soil samples from several spots of the botanical garden Pythium megalacanthum de BARY and P. spinosum SAW. were found. Both species were isolated and cultivated in different culture media. 2. In distilled water Pythium spinosum develops numerouc intercalar conidia which often germ simultaneously in two or three hyphae. 3. The presporangia develop a canal through which their contents passes into the vesicle where the zoospores form. After the zoospores have left the sporangium of P. megalacanthum continues to grow. 4. The membrane of the extending oogonia form with both species long, sparse spines. 5. Pythium spinosum SAW. is a much distributed parasite of the seedlings of summer plants which are cultivated especially in flower gardens (Antirrhinum), and it causes their fall in spring. Otherwise it lives as a saprophytes in the soil of the beds. 6. Pythium megalacanthum de BARY which was formerly described more as a saprophyte, can be likewise such a parasite of garden plants.