ALBERT

Description: Afferent activity in the stellar nerves of Octopus vulgaris has been recorded in response to a probe applying a mechanical stimulus of approximately 5 gm/mm2 to the inner surface of the mantle. Mechanical sensitivity is distributed throughout the mantle surface and there is a large degree of overlap between the peripheral fields of nearby stellar nerves but no overlap of either ventral or dorsal midline. The afferent activity probably results from stimulation of sensory receptors located in the mantle and skin, but antidromic discharge in motor fibres is also possible.

Description: Six lakes of the Wadi Natrun, Egypt, were studied with respect to the chemical composition of their brines and the occurrence of microbial mass developments. All investigated lakes showed pH values of approximately 11 and a total salt content of generally more than 30%. The main components were sulfate, carbonate, chloride, sodium, and minor amounts of potassium. Only traces of magnesium and calcium were present, but unusually high concentrations of organic carbon compounds, nitrogen compounds, and phosphate were found. Mass developments of phototrophic sulfur bacteria, halobacteria, cyanobacteria, and green algae were observed. The functions of complete nitrogen and sulfur cycles in the alkaline brines are discussed. The properties of the lakes and their ecology are compared with data on the Dead Sea and Great Salt Lake, Utah.

Description: Microbiological transformations of sulfur compounds discriminate to various degrees between the stable sulfur isotopes 32S and 34S. Comparatively little is known on isotopic effects associated with sulfur‐oxidizing organisms, and the interpretation of results is complicated since the sulfur pathways are poorly defined and compounds containing two or more sulfur atoms at different oxidation states may be involved. Dissimilatory reduction of sulfate, and sulfite reduction by certain assimilatory microorganisms, causes particularly marked isotopic effects, the expression of which depends on the extent of reaction and other incompletely defined environmental conditions. Models have been proposed to account for these effects based on current knowledge of the reduction pathways. Many of the trends observed during dissimilatory sulfate reduction in the laboratory can also be found in the modern environment leaving little doubt that microbiological factors play a significant role in determining sulfur isotope distributions in nature. However, unusually large isotopic effects, rarely approached in the laboratory, are often observed in nature. The reasons for this are not entirely clear, but in sediments it is possible that diffusional isotopic effects are imposed on biological effects.

Description: Intracellular and extracellular recordings from the stem, gastrozooids, palpons, tentacles and nectophores of physonectid siphonophores are presented. The stem organization previously described for Nanomia applies with only minor differences to Forskalia and Agalma. The endodermal epithelium of the stem is shown to be the pathway for slow potentials. Pumping cycles and feeding activities are organized locally in gastrozooids and palpons. Protective retractions are coordinated, probably through a direct nervous link with the stem. This is also true of tentacles. The ectoderm of bracts is a conducting epithelium; excitation in it can induce nervous activity in the stem, but the mechanism is unknown. Impulse traffic between stem and zooids is erratic and breaks down rapidly with repeated stimulation. The motor centres of the nectophores are connected to the stem by a labile nervous link, but an alternative epithelial pathway exists.

Description: From a series of direct shear and laboratory vane shear tests conducted on natural pelagic and terrigenous marine soils, we have proposed a combined shear test procedure that involves obtaining the total stress failure envelope from tests on only two submarine soil samples. On one of the samples, both the direct shear and vane tests are conducted at zero normal stress. The second soil sample is consolidated under normal stress σn greater than the precompression stress Pc and sheared in a direct shear device under normal stress equal to the above consolidation pressure σn , the laboratory vane shear test on the same sample is conducted under zero normal stress. The combined test program results in four datum points (two from direct shear and two from laboratory vane shear tests. By connecting the two vane test datum points, the cohesion line (the failure envelope corresponding to vane shear tests) is obtained. By connecting the direct shear test datum points (from the soil consolidated under cn 〉 Pc) to the origin of the r vs. σn plane, the part of the failure envelope that lies beyond the precompression load is determined. The part of the failure envelope curve below the precompression stress is obtained by drawing a line parallel to the cohesion line through the direct shear datum point (corresponding to zero normal stress). The data and procedure reported herein indicate that the investigator can realize considerable time savings as well as conservation of sometimes expensive and limited submarine soil samples by using the proposed combined test procedure.

Description: Deep‐sea drilling in the Antarctic region (Deep‐Sea Drilling Project legs 28, 29, 35, and 36) has provided many new data about the development of circum‐Antarctic circulation and the closely related glacial evolution of Antarctica. The Antarctic continent has been in a high‐latitude position since the middle to late Mesozoic. Glaciation commenced much later, in the middle Tertiary, demonstrating that near‐polar position is not sufficient for glacial development. Instead, continental glaciation developed as the present‐day Southern Ocean circulation system became established when obstructing land masses moved aside. During the Paleocene (t = ∼65 to 55 m.y. ago), Australia and Antarctica were joined. In the early Eocene (t = ∼55 m.y. ago), Australia began to drift northward from Antarctica, forming an ocean, although circum‐Antarctic flow was blocked by the continental South Tasman Rise and Tasmania. During the Eocene (t = 55 to 38 m.y. ago) the Southern Ocean was relatively warm and the continent largely nonglaciated. Cool temperate vegetation existed in some regions. By the late Eocene (t = ∼39 m.y. ago) a shallow water connection had developed between the southern Indian and Pacific oceans over the South Tasman Rise. The first major climatic‐glacial threshold was crossed 38 m.y. ago near the Eocene‐Oligocene boundary, when substantial Antarctic sea ice began to form. This resulted in a rapid temperature drop in bottom waters of about 5°C and a major crisis in deep‐sea faunas. Thermohaline oceanic circulation was initiated at this time much like that of the present day. The resulting change in climatic regime increased bottom water activity over wide areas of the deep ocean basins, creating much sediment erosion, especially in western parts of oceans. A major (∼2000 m) and apparently rapid deepening also occurred in the calcium carbonate compensation depth (CCD). This climatic threshold was crossed as a result of the gradual isolation of Antarctica from Australia and perhaps the opening of the Drake Passage. During the Oligocene (t = 38 to 22 m.y. ago), widespread glaciation probably occurred throughout Antarctica, although no ice cap existed. By the middle to late Oligocene (t = ∼30 to 25 m.y. ago), deep‐seated circum‐Antarctic flow had developed south of the South Tasman Rise, as this had separated sufficiently from Victoria Land, Antarctica. Major reorganization resulted in southern hemisphere deep‐sea sediment distribution patterns. The next principal climatic threshold was crossed during the middle Miocene (t = 14 to 11 m.y. ago) when the Antarctic ice cap formed. This occurred at about the time of closure of the Australian‐Indonesian deep‐sea passage. During the early Miocene, calcareous biogenic sediments began to be displaced northward by siliceous biogenic sediments with higher rates of sedimentation reflecting the beginning of circulation related to the development of the Antarctic Convergence. Since the middle Miocene the East Antarctic ice cap has remained a semipermanent feature exhibiting some changes in volume. The most important of these occurred during the latest Miocene (t = ∼5 m.y. ago) when ice volumes increased beyond those of the present day. This event was related to global climatic cooling, a rapid northward movement of about 300 km of the Antarctic Convergence, and a eustatic sea level drop that may have been partly responsible for the isolation of the Mediterranean basin. Northern hemisphere ice sheet development began about 2.5–3 m.y. ago, representing the next major global climatic threshold, and was followed by the well‐known major oscillations in northern ice sheets. In the Southern Ocean the Quaternary marks a peak in activity of oceanic circulation as reflected by widespread deep‐sea erosion, very high biogenic productivity at the Antarctic Convergence and resulting high rates of biogenic sedimentation, and maximum northward distribution of ice‐rafted debris.

Description: Stomach contents of 68 black petrels, Procellaria parkinsoni, 12 Westland black petrels, P. westlandica, and 3 white‐chinned petrels, P. aequinoctialis, were compared. The main prey were Cephalopoda and fish, and these indicated predominantly nocturnal feeding with selection for bioluminescent forms. There is marked latitudinal variation in the Cephalopoda available to these petrels.

Description: Fifty-two species of Ostracoda are distinguished in the Palaeogene succession of Soekor borehole Jc-1 on the continental shelf off Natal. Two species and one new genus are described, and the ostracod faunas can be grouped into four well-defined assemblages. Vertical variations in the make-up of the ostracod faunas, together with various parameters measured in the forminifera populations, are used to discriminate changes in the conditions of deposition and rates of sediment accumulation. These can be summarized: lower Palaeocene environments were hyposaline, restricted circulation, with rapid accumulation; upper Palaeocene through Eocene conditions were normal marine, alternating restricted and open water circulation, with rapid accumulation in the Palaeocene, and slower accumulation in the Eocene; Oligocene conditions were normal marine, with open water given way to restricted circulation, shallow water environments in the upper part. Sediment accumulation rates in the Oligocene vary rapidly, major changes in the composition of the ostracod populations are recognized as important local biostratigraphical events.

Description: in a recent publication von Brandt (1) gives a survey of all determinations of the calcium content of Baltic water hitherto published. He records in all 39 analyses made during the last century, which give us an idea of the order of magnitude of the calcium concentration; they cannot, however, serve for comparative purposes as in many cases chlorine determinations on the same water samples are lacking. Neither have we any clue for judging the accuracy of these analyses, the latest of which date from 1884. Fifty years later, in 1935, Za rin s and O z o 1 ins (8) published an extensive investi­gation of the water in the Bay of Riga and in the Baltic off the Latvian coast, their most westerly station nearly coinciding with the Finnish station F81 (Lat. 57° 22'N., Long. 19°57'E.) above the central depression of the Baltic. Their material comprised about 70 calcium analyses on water from all depths. Finally v o n B r a n d t in the above-mentioned paper publishes nearly 300 analyses of surface water collected in 1935 and 1936 during several voyages from Pillau to Helsingfors and back, and along the German coast as far as Kiel and back. The present material comprises analyses of only 48 samples of surface and bottom water collected during the summer cruise, in July 1935, of the s.s. "Nautilus" from the Gulf of Finland, the Gulf of Bothnia, and the northern half of the Baltic proper. In spite of the smaller number of samples this material is more comprehensive than the two preceding investigations in so far as it covers a greater area of the sea. I t was originally meant as a survey of the calcium content in these parts of the Baltic, but the surprisingly simple relationships between calcium content and chlorinity which it revealed, give the results far more scope than was expected.