The Mechanism of Osmotic Regulation in Artemia Salina (l.): the Physiology of the Branchiae
نویسنده
چکیده
INTRODUCTION In a previous paper (Croghan, 19586) the very great osmo-regulating ability of Artemia has been described. It is clear that in concentrated media the animal must have very well-developed active mechanisms both for excreting NaCl and for taking up water to compensate for the passive movements of these substances into and out of the animal. The staining of localized parts of Crustacea following immersion in dilute AgNO3 solutions and subsequent reduction has been interpreted by Koch (1934) and Krogh (1939) as indicating the site of active ion uptake. But similar staining occurs in Artemia (Dejdar, 1930), and yet this animal in its normal hypertonic medium must be actively excreting NaCl (Croghan, 19586). In this paper further observations on the branchiae of Artemia in relation to the mechanism of osmotic regulation are described. MATERIAL AND METHODS Adult Artemia as described previously (Croghan, 1958a) were used. The basic silver-staining technique is very simple. Animals from a sea-water culture were used for most experiments. The living animal was washed in several changes of distilled water (for 1-2 hr. usually) to remove adherent chloride, and was then placed in io~ M-AgNO3 solution for 2-5 min. The animal was then given a prolonged wash in several changes of distilled water (1-2 hr. usually) to remove any adherent AgNO3, and was placed in photographic developer (1.1.D. 13.) for 1-2 min. to reduce to the black metallic state any silver that had been taken up. The methods used in studying the composition of the haemolymph and of whole animal have been described previously (Croghan, 19586).
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The Mechanism of Osmotic Regulation in Artemia Salina (l.): the Physiology of the Gut
INTRODUCTION In preceding papers various aspects of the osmotic regulation of Artemia have been described (Croghan, 19586, c). The importance of the branchial mechanism excreting NaCl has been discussed (Croghan, 1958c), but it is clear that in order to maintain a haemolymph steady state in hypertonic media a mechanism for the active uptake of water must also be present. The gut epithelium appe...
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