Growth Of Seaweed Research Articles

Water temperature on the growth of sea-weed (I)

Water temperature on the growth of sea-weed (I)

APPLICATION OF FERTILIZERS TO AN OPEN SEA LOCH

INVESTIGATIONS carried out at Loch Craiglin, a small arm of Loch Sween1, have shown that the productivity of an enclosed sea loch can be raised by the addition of sodium nitrate and superphosphate, just as the productivity of a laboratory culture or a freshwater pond can be increased by the addition of plant nutrients. However, the hydrographic and biological conditions in Loch Craiglin were rather atypical: the small depth, the fluctuating and, on the whole, low salinity in the upper layers, the high hydrogen sulphide and low oxygen concentration in the deeper water, the profuse growth of seaweed and eel grass, the soft muddy ground, all were factors which made this experiment a severe test.

The Avonian Succession in the South of the Isle of Man

The Carboniferous rocks described in this paper occur within an area some 8 to 9 square miles in extent surrounding the ancient town of Castletown. The district is coastal and low-lying, a considerable portion being less than 100 feet above sea-level. The highest ground lies north-west of Ballasalla, where a few small tracts rise slightly above 200 feet. The solid rocks are for the greater part obscured by a thick covering of drift, alluvium, or blown sand, and the chief outcrops are on the coast, usually between tide-marks. Most of the inland outcrops are confined to quarries lying west of the village of Ballasalla, to the Silver Burn, and to its tributary the Awin Ruy. The heavy growth of seaweed and the honeycombing of the boring molluscs near low-water-mark render difficult the collecting of fossils, which, in many places, are also partly or totally destroyed by dolomitization, especially near the more important faults. Stretches of sand, shingle, and displaced joint-blocks break the continuity of the beds in the cliffs and on the foreshore, so that direct measurement of thickness is often impossible. The Carboniferous rocks are bounded on the north-west by the Port St. Mary—Arbory Fault, which extends from Perwick Bay to near Ballashimmin (a distance of 5 miles), and with variable throw brings up the Manx Slate Series. Elsewhere on land the boundary is an unconformable or faulted junction with the Lower Palæozoic rocks. A similar junction probably exists a short distance below low-water-mark between the mouth of the

Societies and Academies

DUBLIN. Royal Dublin Society, December 16, 1913.—Dr. J. H. Pollok in the chair.—Prof. K. Yendo: Cultivation of sea-weeds in Japan. Sea-weeds are extensively used in Japan as food, glue, and manure. The annual amount of production is estimated at about 800,000l, of which 300,000l worth is exported, chiefly to China. The most important point in cultivation is to give the plant a suitable ground for attachment. Various factors, such as depth, light, salinity, temperature, nature of substratum, movement of water, &c, have great influence in limiting the growth of sea-weeds in a certain locality. The author explains these factors with reference to plant-life in the sea, and describes the modes of cultivation in Japan.—Dr. G. H. Pethybridge: Further observations on Phytophthora erythroseptica, Pethyb., and on the disease produced by it in the potato plant. The peculiar mode of development of the sexual organs (intra-antheridial growth of the oogonial incept) described for this species by the author in a former paper, and shown by him to occur also in P. infestans and P. phaseoli, has been found in P. parasitica, Dast., and P. colocasiae, Racib., by Dastur, and by Butler and Kulkarni respectively. In the present paper the production of zoospores and of germ tubes by the conidia and the mode of germination of the oospores is described for P. erythroseptica. The inner thickened part of the oospore wall is composed of cellulose, and previous to germination becomes dissolved, so that it thus appears to serve not only as a protective covering for the spore, but also as a store of reserve carbohydrate. The fungus with its reproductive organs has now been found in all the underground portions of the potato plant. It is the cause not only of a specific rot of the tubers, but of a disease of the plant as a whole, of the “wilt” type, the outward symptoms of disease being rather similar to those produced by Bacillus melanogenes, Pethyb. and Murphy.—Prof. H. H. Dixon: Note on the spread of morbid changes through plants from branches killed by heat. Experiments are described showing the possibility of washing out the poisonous materials liberated in the water tracts of branches killed by heat, and thus removing the contamination from the water supply of the leaves above. The withering of the leaves on a killed branch may in this way be long postponed. It is also possible to wash back the contaminating substances from the dead branch into other branches, when it is found that the leaves on the otherwise uninjured branches wither. Both these experiments show that it is not allowable to assign the withering to a failure in the water supply brought about directly by the death of the cells of the heated branch.—W. R. G. Atkins: Oxydases and their inhibitors in plant tissues. Part iii., The localisation of oxydases and catalase in some marine algae. Catalase was found in all algae tested. Out of a total ot twenty-nine, only one alga gave the direct oxydase reaction, while six gave the indirect with guaiacum. In two cases only was a colour produced with α-naphthol.—Prof. T. Johnson: Bothrodendron kiltorkense, Haughton, sp.: its cone and Stig-marian stage. The specimen described supplies conclusive evidence that the Stigmarias found in the Kiltorcan quarry are the underground root-carrying rootstocks of Bothrodendron. In one specimen organic continuity is shown between the aërial stem with typical leaf-scars and Stigmaria with apoendages, a horizontal line of demarcation indicating the ground level. The paper also contains a description of a fertile shoot ending by repeated forking in four tips of which three are stalked cones, 3×5 cm. in extent, the fourth being sterile.