Natural and experimental hosts ofEchinococcus granulosusandE. multilocularis, with comments on the genetics of speciation in the genusEchinococcus

Within recent years, problems of host-parasite relationships have been receiving increasing attention from parasitologists. This is particularly true in the study of the cestodes Echinococcus spp., where predilection for different hosts—when considered with the morphology of the adult and the growth and development of the larva—seemed sufficiently significant to lead to the establishment of the two species, E. granulosus and E. multilocularis. Much experimental and field work has been carried out on a variety of vertebrate hosts and a number of new, naturally infected and laboratory hosts have been reported. A survey of intermediate and definitive hosts has been undertaken in this laboratory as part of a study to investigate whether factors of morphological, physiological or biochemical origin were concerned in host specificity. These data, together with some genetical considerations, form the basis of the present paper.