[Epidemiologic and parasitologic survey concerning the Hassan Addakhil dam and branches to the Tafilalet province (Morocco, May-June 1975)].

In conclusion we know human and animal gathering is usually required for the development of water invertebrate populations, and particularly Bulinus contortus or Culicidae larvae, in a water system polluted with excrements or sewage. Such conditions are not those of Hassan Addakhil lake and the latter is not to-day, on its surface, a source of contamination. As we report p.

[Study of the molluscocid properties of lead triphenylacetate].

The molluscicide and biocide properties of lead triphenylacetate (4,5 p p m, on Biomphalaria glabraia and Bulinus contortus) are not so great that the toxic action of tin tributiloxyde, on the same snails (2 p p m). Still the prices of the organic salts of lead are not so expensive as tin organic salts.