title: Observations on two biological races of Schistosoma mansoni.
mesh_terms: D000818:Animals; D001700:Biomphalaria / Q000469:parasitology; D005260:Female; D006790:Host-Parasite Interactions; D006824:Hybridization, Genetic; D008297:Male; D051379:Mice; D012550:Schistosoma mansoni / Q000033:anatomy & histology / Q000472:pathogenicity / Q000502:physiology*; D013045:Species Specificity; D014774:Virulence