Experimental and cytological studies on bisexual and hermaphrodite free‐living nematodes, with special reference to problems of sex

Abstract

Abstract Hermaphroditic gonads of Rhabdites elegans can be distinguished in early developmental stages, but oogonia cannot be told from spermatogonia. Certain peculiar males show developmental processes approaching those of hermaphrodites. More eggs are produced by a hermaphrodite than there are sperm with which to fertilize them. Such exhausted hermaphrodites may be mated with males and produce fertile eggs, but convincing evidence of cross‐fertilization is lacking. Unmated females of Diplogaster aerivora live longer than mated ones, but no difference was found in the males. Sexual instinct seems to be lacking in males of R. dolichura and R. elegans. Hermaphrodites mated with males produce many more male offspring than by self‐fertilization, but these do not exhibit sexual instincts. Females produced by cross‐fertilization are not pure females, nor have they been found at all in R. elegans or R. dolichura. After fertilization in these two species, both polar bodies are formed and the pronuclei fuse. Sex is determined by the form of sperm.