Experimental Cytological Evidence for an Outward Secretion of Water by the Nephric Tubule of the Crayfish

Maluf, N. S. Rustum

doi:10.2307/1537627

Cited by 12 publications

(2 citation statements)

References 6 publications

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“…Martin (1957, 1958) points out that data originally presented by Maluf (1940Maluf ( , 1941 as evidence for secretion may equally be interpreted in support of filtration. It appears, therefore, that the composition of the urine is modified during passage down the excretory tubule.…”

Section: ( I ) Generalmentioning

confidence: 99%

“…The means by which the primary urine is caused to enter the excretory tubule is still not clear and considerable controversy has surrounded the rival theories of filtration and secretion . Martin (1957, 1958) points out that data originally presented by Maluf (1940Maluf ( , 1941 as evidence for secretion may equally be interpreted in support of filtration. If urine is to be formed by ultrafiltration there must be an adequate pressure difference between blood and urine.…”

Section: ( I ) Generalmentioning

confidence: 99%

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The Osmoregulation of Crustacea

Lockwood

1962

Biological Reviews

153

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CONTENTS ( I ) Types of regulationThe relation between blood concentration and medium concentration in animals acclimatized to a range of salinities has been extensively studied. Some of the results of such experiments are shown in Figs. 1-4. Three primary types of response to changes in salinity are known (Fig. I).(I) T h e blood is almost isosmotic with the medium over the entire salinity range tolerated. Animals with this type of response are known as conformers.( I ) Isosmoticity between blood and medium over a wide range of concentration is confined to forms of marine origin. Species showing this type of response include Maia squinado, Portunus depurator (Margaria, 193 I ) ; Hyas aranm, Callianassa afinis, Upogebia sp., Cancer antennarius, C. gracilis, Pugettia producta and Emerita analoga (Gross, 1957). With the exception of Upogebia and Callianassa, which burrow in sand or mud, all these are essentially sublittoral forms which, in nature, are likely to be exposed to only small changes in the salinity of their medium. Correlated with this normal constancy of their environment, tolerance of variation in the concentration of their medium is limited in extent. Maia squinado has been acclimatized to 80 yo sea water (Duval, 1925), Emerita analoga to 75% sea water (Gross, 1957) and Hyas * But see Addendum. 260A. P. M. LOCKWOOD urunetl~ to 50 yo sea water (Schlieper, 1929), but the animals die if maintained in lower salinities. Even smaller changes in concentration apparently affect the viability of many marine forms, either directly or through the inability of organisms on which they are dependent to tolerate dilutions. Dahl (1956) has found that 75 % of the species found in the Skagerrack disappear when the salinity falls from 34 to 30 parts per thousand in the Kattegat.(2) Estuarine and coastal species are normally exposed to dilutions of sea water and they display a variable but limited capacity to maintain the blood hyperosmotic to dilute media. The gradient maintained between blood and medium increases as the 262 A. P. M. LOCKWOOD Crangon from brackish water migrates seaward for the winter months (Broekema, 1942 ; Lloyd & Yonge, 1947). Palaemonetes and Gnorimosphaeroma are principally estuarine and salt marsh forms.(2) Osmotic regulation of terrestrial forms Terrestrial forms depend, to a considerable extent, on behavioural mechanisms to supplement the part played by physiological processes in the regulation of the blood concentration. Gross (1955) has shown that Birgus latro can regain the normal blood concentration, when this has been altered, by selecting water of the appropriate salinity to drink. Drinking has also been observed in the isopods Oniscus asellus, Porcellio scaber and Armadillidium vulgare whilst Ligia oceanica takes up water through the anus (Spencer & Edney, 1954). The crab Coenobita perlatus spends 90% of its time out of water, but cannot maintain its blood concentration at the normal level unless allowed access to both fresh water and sea water (Gross & Holland, 1960). The less terrestr...

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Section: ( I ) Generalmentioning

confidence: 99%

Section: ( I ) Generalmentioning

confidence: 99%