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A preliminary study of adaptation and inhibition of reflex claw opening in the crab Potamon perlatus (Milne Edwards)

- Bush, Brian M H

Authors: Bush, Brian M H
Date: 1956
Subjects: Crabs , Decapoda
Language: English
Type: Thesis , Masters , MSc
Identifier: vital:5906 , http://hdl.handle.net/10962/d1014683
Description: The only recorded experimental attempt to determine the functional, biological significance of peripheral inhibition in the Crustacea is that of Hoffmann (1914). From a series of experiments on Astacus fluviatilis L. involving transsection of the opener inhibitor and motor axons of the cheliped, he concluded that the opener inhibitor axon of the claw responded to prolonged or repeated sensory stimulation by transmitting inhibitory impulses to the opener muscle, the peripheral inhibition thus evoked causing adaptation of the reflex opening responses of the claw to the sensory stimulation. This suggests that there may be (1) a very high degree of peripheral control of (a) the reactions of the animal to external stimuli, and perhaps also to proprioceptive stimuli, and therefore (b) of the behaviour of the animal; and (2) a correspondingly high degree of independence of this behaviour from central nervous control. It is therefore of importance to discover whether, in fact, this conclusion is valid for Astacus and other Decapod Crustacea, and if so, then to what extent the adaptation is peripherally controlled. A preliminary attempt haa been made to repeat these experiments of Hoffmann, using Potamon perlatus (M.Edw.). Experiments in which mechanical sensory stimulation was used to evoke reflex claw opening indicated that this conclusion is not applicable to P.perlatus. The adaptation of the mechanical claw openining responses which occurred with repeated sensory stimulation was not affected by transsection of either the specific opener inhibitor axon or the common inhibitor axon of the claw. It was evidently mainly due to sensory adaptation when the sensory stimuli were heavy, and to centrally controlled adaptation when the sensory stimuli were light. The significance of these results is discussed. Other effects observed during the course of the work, of electrical "sensory" stimulation, and of cerebral ganglion elimination, are also described and discussed in relation to the present problem.
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Date Issued: 1956

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Lovedale

- South Africa. Surveyor General's Office

Authors: South Africa. Surveyor General's Office
Date: 1956
Subjects: 1 inch = 20 roods 30.5595° S, 22.9375° E , Lovedale Institution Maps , Alice (South Africa) Maps , South Africa History 1806-1909 Maps
Language: English
Type: maps , digital maps , cartographic
Identifier: http://hdl.handle.net/10962/109943 , vital:33207 , Cory Library for Humanities Research, Rhodes University Library, Grahamstown, South Africa , MP476
Description: Plan of land around Lovedale; some of it marked for "alienation" - owners of some property shown. (Negative) Photograph of origincal manuscript, 1875.
Full Text: false
Date Issued: 1956

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Port Elizabeth (3421)

- Trigonometrical Survey (South Africa)

Authors: Trigonometrical Survey (South Africa)
Date: 1956
Subjects: 1 : 1000000 30.5595° S, 22.9375° E , Port Elizabeth (South Africa) Maps , Eastern Cape (South Africa) Maps , South Africa History 1910-1961 Maps
Language: English
Type: maps , digital maps , cartographic
Identifier: http://hdl.handle.net/10962/115984 , vital:34286 , Cory Library for Humanities Research, Rhodes University Library, Grahamstown, South Africa , MP1798
Description: Port Elizabeth (3421). Aeronautical chart of Port Elizabeth region, South Africa. Compiled and drawn by the Trigonometrical Survey Office, 1953. Reprinted by the Government Printer in 1956. Hypsometric tints for Africa south of 16° south latitude. Elevations in feet. T.S.O. 607/836. Topographic base, 1952. First edition.
Full Text: false
Date Issued: 1956

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