Penetration gland secretion by hexacanths of Hymenolepis diminuta

The rate of expulsion of penetration gland material was determined from photomicrographs of Hymenolepis diminuta hexacanths stained with neutral red dye at intervals after hatching in vitro. Identical secretory rates were recorded for hexacanths incubated in either Tyrode's solution or Tyrode's solution plus an extract of the midgut of Tenebrio molitor. In both media the reduction in stained material observed in the glands after 135 min incubations was equivalent to that observed for hexacanths that had had opportunity to penetrate in vivo during the same time period. These results were interpreted as indicating that the in vivo secretory pattern was similar to that observed in vitro, and that chemical stimuli from the tissue extracts were not required to initiate secretion. Microdensitometric readings also demonstrated a quantitative decrease in dye within the glands as incubation time increased. Ultrastructural examination of the glands showed that their secretory inclusions were exported via ducts to the epithelial cytoplasm where they accumulated in discrete blebs enclosed by the surface membrane. These inclusion-filled, membrane-bounded blebs were apparently formed and released continuously until, after approximately 2 h, only a few inclusions remained in the penetration glands.

Techniques for pheromone bioassay studies of ants

Techniques and apparatus developed for pheromone bioassay studies of ants are described. They include a ventilated cage, with a blacked-out nest area and a two-compartment arena, in which colonies are maintained in the laboratory, and in which group experiments are carried out; a prey treatment apparatus, in which a stinging ant is clamped at the junction of head and thorax, with its body supported on a length of black nylon tubing which is used as artificial prey after it has been stung for a specified period; an applicator for introducing into the cage artificial prey which have been treated with ant secretions, either by the latter method, or by the direct application of dissected gland material; and a closed-system, pheromone-testing apparatus, in which an ant is held in a perspex observation chamber with controlled lighting, supplied with air at constant temperature, relative humidity and flow rate, and treated with gland odours introduced into the conditioned air.

Properties of the Minerals in the Exuvia of Crustacea

An unusual reaction between material in the exuviae of Crustacea and pure cold mercuric chloride, resulting in the deposition of a bright red compound, led to the discovery that, contrary to expectation, the inner surface of the fresh moult, and even of the inter-moult exoskeleton, is strongly alkaline (pH = 9.1). This is near the optimum for both alkaline phosphatase and carbonic anhydratase, which both may be active in resorption of mineral preparatory to ecdysis. Correlations between the distributions of the red Hg-compound, phosphate, carbonate, alkaline phosphatase, and pigmentary pattern have been found in various Crustacea. The reaction with cold HgCl2 is given also by the millipede exoskeleton, the molluscan shell, the calciferous gland-material of earthworms (pH 9.2-9.4) and by calcareous sponges, but not by echinoderm or vertebrate skeletons, and not by the exoskeleton of insects, spiders, and centipedes, which lack mineral. The compound(s) with mercuric chloride are probably chiefly oxychlorides. A steady, if slight, solution of the skeletal carbonate and phosphate is necessary to maintain the observed high pH, and to permit the formation of these mercury-compounds.