THE DEVELOPMENT OF THE SEXUAL ORGANS IN LEPTOLEGNIA CAUDATA

Abstract

Leptolegnia is one of the less common genera of the Saprolegniaceae and until recently has been represented by only one species, L. caudata deBary. This species was first tentatively placed in Saprolegnia by deBary (I2), but later (I3) he established the genus Leptolegnia based on the one species. The mycelium is typically composed of a circular, whitish fringe of regular threads around a fly or other insect or bit of seed in water. The strains vary considerably in their robustness, the form from Chapel Hill being considerably less robust than those from Long Island or Florida, the threads of the latter often approaching a well developed Saprolegnia in thickness and length. The sporangia, in their thread-like character, resemble those of Aphanomyces, though the behavior of the spores in Leptolegnia is more like that of the spores in Saprolegnia. The otogonium in Leptolegnia shows a superficial resemblance to that of Aphanomyces in that each contains only one egg. The beak-like process on the oogonium, which usually grows out where the antheridia are applied, the exceedingly thick oospore wall, the peculiar eccentric arrangement of the oil globules in the ripe oospore, and the fact that the oospore completely fills the oogonium are characters which make this genus stand out from the other genera of the Saproiegniaceae. The ripe oospore of Pythiopsis cymosa, however, with its lunate cap of oil globules is quite similar to the oospore of Leptolegnia. Although the fungus has been reported from a number of diverse regions its occurrence is rather infrequent. In Europe it has been reported from Germany by deBary (I2, 13), Fischer (I4) and von. Minden (i8); from Denmark by Muller (2I) and Petersen (25); and from Latvia by Apinis (I). In America it was first reported from North Carolina by Coker (7) and has since been collected by Thaxter in New England, by Pieters at Ann Arbor, Michigan, in Florida, and on Long Island, N. Y. (see Coker, 8). It is interesting to note that Petersen (25, P. 5II) and Muller (2I) record the fungus as an exceedingly destructive parasite on Leptodora Kindtii.