Electrophoretic studies of some planorbid egg proteins.

Morphological characters alone have so far failed to provide adequate criteria for the identification of the molluscan intermediate hosts of African schistosomes. In the course of investigations into various other taxonomic approaches, it has been found that the egg proteins, when subjected to electrophoresis, are sensitive indicators of differences at the population level. About 80 populations of various species of African and Neotropical planorbids have been examined in this preliminary study. Differences at the population level have a considerable bearing on relationships between the snails and the larval schistosomes that parasitize them and help to explain the evolution of local races of schistosomes.