Uniparental Miracidia of Schistosomatium douthitti and their Progeny (Tremaoda, Schistosomatidae)

In a paper to be published elsewhere I show that females of Schistosomatium douthitti mature sexually in definitive hosts (mice) in the absence of males; that these females lay eggs and that many such eggs develop parthenogenetically, giving rise to uniparental miracidia. It is pointed out that in unisexual infections with female S. douthitti development of miracidia is not sporadic and unpredictable, but is of regular occurrence. During the experiments mentioned above, examinations were made of the eggs in fresh tissues (intestine, liver, spleen and lung) removed from hosts carrying ? and 6-?infections. These examinations revealed no differences between the uniparental miracidia and those from biparental infections. However, it was thought desirable to make further studies on m;racidia f-^m both sources to detect, if possible, any abnormalities in the uniparental miracidia which might have resulted from lack of fertilization of the eggs from which they developed. It was also considered of interest to determine whether miracidia derived from unfertilized eggs could penetrate snails and give rise to cercaria-producing infections. That uniparental miracidia are infective for snails has been demonstrated, and an abstract (Short, 1948) gives some results of these experiments. The present work is concerned with studies on the morphology, behavior and size of uniparental miracidia and a comparison of such miracidia with those from biparental infections. This paper also presents, in more detail than given previously, results of exposing snails to uniparental miracidia and an account of the progeny thus derived. All my unpublished results referred to in the present paper are containd in a paper entitled Sex Studies on Schistosomatiumn douthitti (Cort, 1914) Price, 1931 (Trematoda: Schistosomatidae). (Amer. Midland Naturalist, in press )