Abstract. Each of four Fucus species occurring on the Atlantic coast of Canada was presented to two species of gammarid amphipods in no-choice and multiple-choice laboratory experiments. We also measured concentrations of anti-herbivore phlorotannins in each of the Fucus species. The study site was Cranberry Cove in Nova Scotia, Canada, and experiments were conducted in 1988. In a multiple-choice experiment, E vesiculosus was very heavily grazed. Other species were much less affected. In a no-choice experiment, E evanescens, E spiralis and E vesiculosus were eaten at similar rates, while F. distichus was barely grazed. These results correlate with measurements of phorotannin concentrations in each of the species. E distichus had much higher concentrations than did the other species (which were not significantly different among themselves). There is no general clear-cut relationship between grazer deterrence and competitive capability within the fucoid guild studied.

Using the Folin-Denis assay, we demonstrated significant ( p < 0.05) differences in phlorotannin concentrations among large and small individuals of Fucus vesjculosus. This finding correlates with previously published differences in grazing susceptibility among the 2 size-classes of plants. However, in 2 other species of Fucus (F. evanescens and spiralis), there were no significant differences ( p > 0.05) in phlorotannin concentrations among size-classes.Therefore, concentrations of anti-herbivore con~pounds cannot explain different effects of grazers on large and small individuals of F. spiralis.

Silver nitrate stains the following elements of the Oedionychina spermatogenesis: Kinetochores, paracentromeric blocks, a number of interstitial bands in post-diplotenic Y chromosomes, parsfibrilhis of postdiplotenic intra-and extranuclear nucleoli. Chromatidal kinetochores of the large sex chromosomes remain close together, in agreement with the earlier observation that these univalents orientate syntelically at M I.Staining of paracentromeric blocks is supposed to be a concentration effect of stain, due to positive heteropycnosis. The presence of Ag-bands in the Y chromosome coincides with an abundant formation of Ag-positive fibrous prenucleoli which soon develop a granulous, less Ag-opaque component. Similar staining relations between fibrous and granulous components are seen in the cytoplasmic nucleolus equivalents at the "nuclear sieve complexes". Ag-banding of the Y chromosome is both stage and species depending, and useful for cytotaxonomy if evaluated with caution.

A nucleolar substance adjacent to early prophasic sex bivalents is observed and studied by cytochemical means in certain broad-nosed male weevils. The substance soon disintegrates, possibly because of an active nucleolus organizer. By early diplotene, the sex bivalent assumes a parachute shape (Xyp). An argyrophilous, fibrous substance appears first at the inner borders of X and y, then invades the whole space between them. Most commonly used nucleolus and protein stains leave it unmarked. RNA and histones seem to be excluded. Only AgNOR staining marks the substance clearly, especially if a formalin-containing fixative has been used.

BRIEF NOTES ON THE CYTOLOGY OF NEOTROPICAL COLEOPTERA 4. CHALCOLEPIDIUS SILBERMANNI CHEVROLAT (ELATERIDAE:PYROPHORINI)