Small Algae Research Articles

The Ecology of Lough Ine: IX. The Flora and Fauna Associated with Undergrowth-forming Algae in the Rapids Area

at the north and south ends of the Rapids the currents do not exceed about 01 m/sec (Bassindale et al. 1948). Organisms inhabiting the fronds of the large brown algae (Saccorhiza polyschides and Laminaria digitata) are exposed to the current, but those inhabiting sub-littoral boulders or small algae are partly sheltered by the overlying canopy of fronds, which forms a slippage plane (Kitching et al. 1952). Nevertheless there are striking differences in the fauna of boulders off Mark 7 and from more sheltered regions (Lilly et al. 1953), which are probably to be explained in part by secondary influences of the current, such as the control of sedimentation. For this work seven stations were chosen to provide a comparison between the Lough (Codium Bay and Renouf's Bay), the Rapids (Stations Nos. 1, 3 and 5), and Barloge

On the Nutrition of Ochromonas

ABSTRACT A species of the chrysophycean genus Ochromonas from England was grown in pure culture and compared with similar strains isolated in the United States. Although these organisms possess chromatophores with chlorophyll, they need organic substances not only as a source of nitrogen compounds, but as independent carbon and energy sources; they also require certain growth factors. Peptones are better as nitrogen sources than single amino-acids, few of which give satisfactory results. The utilization of inorganic nitrogen could not be demonstrated. As carbon sources sugars, alcohols, and fats, and, to a lesser degree, acetate, are suitable. Growth factors contained in liver extract, milk and yeast autolysate, and in smaller amounts in most peptones, are indispensable. Enzymes hydrolyzing starch, sucrose, fat, and protein are excreted. Ochromonas ingests and digests starch grains, casein, oil droplets, and small organisms. Neither bacteria nor yeast nor small algae were found able to support growth of any of the strains, even in the light. An additional carbon compound and possibly special vitamins are required. The hypothesis is put forward that phagotrophy chiefly serves for obtaining chemical compounds which the cell cannot synthesize itself and which have the character of vitamins. Phagotrophy therefore supplements the other means of nutrition, in the main qualitatively, while sugar, &c., supplement it quantitatively and are indeed indispensable. The same media which support ample growth in the light do so also in the dark. This shows that photosynthesis is of little importance for the growth of the organisms, although it keeps them alive for long periods, while in the dark they soon die. Correlated with the manifold ways of acquiring food, there is also a remarkable variability in the size and shape of the cells, and still more in the dimensions and pigmentation of the chromatophores, and in the reserves stored as leucosin, volutin, and oil. These features which now prove to depend so much on conditions have previously been widely used in the diagnosis of species. The basis of classification should therefore be revised. Apart from the stigma, which is specific, use ought to be made only of those characters whose variation with conditions is reasonably well known. The extraordinary nutritional versatility of Ochromonas is considered to be a primitive character. From ancestors with a mixed nutritional habit, phototrophic, phagotrophic, and saprotrophic flagellates seem to have evolved, each with only one of the three modes of nutrition that are combined in Ochromonas.

テングサの増殖に關する研究

The germination and the initial debelopment af this alga have been reported by the authors in their previous papers. And ofterward they pursued the postembryonal stage of the alga by the cultures of the sporelings in laboratory and in natural condition at sea. As a rule sporelings rise up vertically, and then secondary shoots sprout from the basal part of the main axia. In one case allmost all secondary shoots rise up erectly and they form an upright bush, in the other case all the lateral buds sprout horizontary and grow creeping stlons, emitting new upright buds and rhizoids (Fig. 2). Young plants grow very slowly at the begining, from summer till winter, and then they begin to grow rapidly (Fig. 5). The young plants are damaged by dense covering of another small algae or feeding of Gastropoda.

Browsing of Patella

THE food of Patella vulgata, so far as we know at present, consists mainly of small Algae including diatoms1 which it scrapes from the rocks by means of its radula, but it will also eat larger plants2. Orton3 included a note on Patella eating food-paths in green Algae on piers. Moore and Sproston4 noted that the growth of Algae was limited by the browsing of limpets, and Moore5 has estimated their food requirements from observations on individuals clearing an algal felt. The importance of this browsing habit in connexion with foreshore ecology does not, however, appear to have been sufficiently realized. The following experiment illustrates this importance in striking fashion.

Transportation of rock by kelp

In addition to being rafted by ice and by drifting logs, pebbles may be carried by kelp holdfasts to be dropped into deep-water sediments after the floating kelp has decayed or been eaten. Many shallow-water organisms similarly may be deposited in foreign environments. Numerous pebbles and cobbles still attached to kelp have been picked up on beaches, and in at least two instances pebbles with remnants of holdfasts have been found in relatively deep dredgings of the ocean floor. Although large kelps with floats are limited essentially to the Pacific and Antarctic regions, smaller algae from other coasts are also known to raft pebbles and shells long distances.

The Bionomics of some Tree-hole Mosquitos

1. 138 larvae of Anopheles, Finlaya and Orthopodomyia, collected from three tree-holes described in Part I, were dissected and their contents examined.2. Small algae, a few animals, bacteria and considerable quantities of rotting vegetation were found in them.3. The algal and animal food seems to be insufficient for the anabolic processes of the larvae.4. It is possible that bacteria may play some part in their nutrition, especially of Orthopodomyia.5. It is also suggested that the larvae are able to utilise any food constituents present in the vegetable debris.I wish to thank Dr. P. A. Buxton for the interest he has shown during the progress of this work, and Professor F. E. Fritsch for help in identification of the algal species.

PICRO‐NIGROSIN, A COMBINATION FIXATIVE AND STAIN FOR ALGAE

Pfitzer (i) used a saturated aqueous solution of picric acid, to which he added a varying amount of an aqueous solution of nigrosin, to kill and stain minute forms, such as diatoms and small algae, under the cover glass. Freeborn (2), Pianese (3), and Johnston (4), and other zoological investigators have employed picro-nigrosin alone, or in combination with other stains, with excellent success, but there is little reference to its use by botanists. The writers, by independent study, have found it a valuable stain for filamentous algae and for younger tissues of forms with denser structure, and believe that the results of their experimcnts, which confirm Pfitzer's results in practically every detail, are of sufficient interest to warrant this brief note. The combination fixing and staining solution, which may be used several times without apparent deterioration, was prepared by saturating a saturated aqueous solution of picric acid with Gruebler's water-soluble nigrosin. Material was placed in this solution for from three to twenty-four hours, rinsed in water to remove the excess stain, and run through the grade alcohols with half hour intervals, to glycerine, clove oil, Venetian turpentine or balsam. The general result, regardless of variations in the method after the material has been run through the alcohols, is a blue-black coloration of the nucleus and nucleolus, a faint blue in the pyrenoid and cytoplasm, an almost colorless chromatophore, and a colorless cell wall. The stain is unusually transparent, differentiating the nuclear structure in cells and tissues with dense cytoplasm. For immediate class use, algae were studied in 70 per cent alcohol or transferred to a mixture of alcohol and glycerine which served to clear fairly well and prevented the mount from drying up during the laboratory exercise. Some of the best results were obtained with material transferred from absolute alcohol to clove oil and examined in the latter. Excellent permanent mounts were made by following Chamberlain's Venetian turpentine method

Das botanische Practicum

THE third edition of this well-known book has been so favourably received that a fourth edition has now been published. The alterations and additions in this new issue are not so extensive as in the previous one, but they are nevertheless considerable, and the whole book has been subjected to careful revision. The scope of the book has certainly advanced beyond the author's original intention as conveyed by the title, “Introduction to the Personal Study of Microscopic Botany,” for there are references to several important facts which are highly interesting, but the experiments connected with them one would not think of undertaking unless they formed part of an original investigation; parthenogenesis in Marsilia and the problem of intramortal or intravital staining are notable instances. As the facts are stated without critical opinions being offered, a simple reference to the publications would have been as valuable, and would have made a reduction even though slight in the size of the book. However, the greater number of the additional paragraphs are of considerable practical value, and not the least so are the directions or hints which emanate from Prof. Strasburger himself or from workers in his laboratory, as, for instance, the method of examining the root of Vicia Faba, the directions for embedding small algae and the instructions for demonstrating protoplasmic threads (Plasmodesmen). Other notable additions include new tests for starch, fats, callus and cork, and the use of neutral violet as a reagent for pectic compounds. Darwin's device of using hornshavings as a hygrometer to determine the number of stomata and Buscalioni's collodion method for the same purpose are mentioned, and some account is given of Brown and Escombe's work on the diffusion of gases through small apertures. It will be found that this edition differs mainly by the insertion of new paragraphs, and practically the only chapter which is rewritten is the last, dealing principally with cell problems.

On some Foraminifera from the Loo Choo Islands

ABSTRACT A Pressed and mounted specimen of a small alga, labelled “Laurencia paniculata, Loo Choo Islands,” was recently sent to me by Dr. E. Perceval Wright, with the suggestion that some Foraminifera which had been entangled in its meshes might be worth examination, and that at any rate it would be interesting to know what particular species had lived amongst its miniature branches. As the sea-weed itself was of some value, two or three inches were taken, and the portion as separated yielded examples of the following species of Foraminifera, some of them in sufficient number to supply two or three good mountings.