Summary1.Spores of several species of Mycetozoa includingReticularia Lycoperdon, Fuligo spetica, Stemonitis splendensvar.flaccida, Lycogola epidendriimandTrichia varia, have been successfully germinated in artificial solutions.2.The rate of germination varied in the different species;Reticularia Lycoperdontaking about an hour,Trichia variaabout five days.3.Tables are given showing the proportion of germination and the time taken, in respect to a number of organic substances. The effect of light, darkness and combined darkness and heat was tried. The results differ in the various species and no general conclusions could be arrived at.4.Evidence is brought forward to show that the length of time taken by the spores of a species collected from different localities to germinate does not differ appreciably, no more than do the spores of the same mass of sporangia when grown at different times under the same conditions. It has been found that the spores ofReticularia Lycoperdondo not loose their vitality in five years, though after seven years germination is uncertain. The same vitality is not shown by other species,Trichia varialosing its power of germination in about a year.Our thanks are due to Professor R. R. Gates for reading through the proofs and for helpful criticisms during the work.