The cellular features of mercury and selenium accumulation has been studied by transmission electron microscopy and x-ray microprobe analysis in the liver of striped dolphins. Mercury and selenium occurred as dense intracellular granules, located mainly within the liver macrophages (Kupffer cells). Granules were composed of 150 A spherical particles showing the same electron diffraction pattern and x-ray spectrum as mercuric selenide. The role of macrophages in mercuric selenide granule production and storage is discussed.

The effects of environmental temperature on haemocyte antibacterial activity were investigated for the shore crab, Carcinus maenas. Haemocyte lysate supernatants (HLS), prepared from groups of five animals (sampled at monthly intervals over one year and covering a range of temperatures) were assayed for their ability to reduce viable counts of the marine bacterium Psychrobacter immobilis NQMB 308 during 4 h incubation. Parallel measurements were made of HLS protein concentration, total haemocyte count and ambient aquarium sea-water temperature. Despite wide variation in the values derived for each parameter, the results show that powerful antibacterial activity was present in HLS for all months except February and August, when respective aquarium water temperatures were at their lowest and highest for the year. This emphasizes the importance of environmental factors in immune capability: a phenomenon of significance not only to commercial shellfish culture but also for the use of immune parameters as biomarkers of environmental disturbance.