Diatoms sentence example
It has been found possible to grow pure cultures of various diatoms, and by feeding these to delicate larvae kept in sterilized sea-water, great successes have been attained.
In some cases both the nucleus and the chromatophores may be carried along in the rotating stream, but in others, such as T.Titeila, the chloroplasts may remain motionless iii a non-motile layer of the cytoplasm in direct contact with the cell wall.i Desmids, Diatoms and Oscillaria show creeping movements probably due to the secretion of slime by the cells; the swarmspores and plasmodium of the Myxomycetes exhibit amoehoid movements; and the motile spores of Fungi and Algae, the spermatozoids of mosses, ferns, &c., move by means of delicate prolongations, cilia or flagella cf the protoplast.
Filamentous diatoms may be mounted like ordinary seaweeds, and, as well as all parasitic algae, should whenever possible be allowed to remain attached to a portion of the alga on which they grow, some species being almost always found found parasitical on particular plants.
Ordinary diatoms and desmids may be mounted on mica, as above described, by putting a portion in a vessel of water and exposing it to sunlight, when they rise to the surface, and may be thus removed comparatively free from dirt or impurity.
It is probable that some are carnivorous, either attacking other larvae or subsisting on more minute forms of animal life; but others perhaps feed more exclusively on vegetable matters of a low type, such as diatoms.Advertisement
These cilia pass on any diatoms and -_„ other minute organism which come within their range of action to the -_-„ capacious oval mouth, which appears as a mere 10 --- deepening of the gutter in the middle line.
The limestones contain Globigerina and other Foraminifera, the siliceous beds are made of Radiolaria, sponge spicules and diatoms, while the red clay closely resembles the red clay of the deepest parts of the oceans.
The polypide consists of a "lophophore" bearing a series of ciliated tentacles by which Diatoms and other microscopic bodies are collected as food, of a U-shaped alimentary canal, and of a central nervous system.
It has been found sporadically near the Aleutian Islands, between the Philippines and Marianne Islands and to the south of the Galapagos group. It is made up to a large extent of the siliceous frustules of diatoms. It is usually yellowish-grey and often straw-coloured when wet, though when dried it becomes white and mealy.
Brown or even blood-red stripes have been observed in the North Atlantic when swarms of the copepod Calanus finmarchicus were present; the brown alga Trichodesmium erythraeum, as its name suggests, can change the blue of the tropical seas to red; swarms of diatoms may produce olive-green patches in the ocean, while some other forms of minute life have at times been observed to give the colour of milk to large stretches of the ocean surface.Advertisement
Sometimes the gyttja consists mainly of diatoms, and is then called bergmjiil.
The Copepoda live upon the diatoms and other important microscopic vegetable life at the surface of the sea, and in their turn serve as food for fishes and other larger forms and thus, indirectly, for man himself.
Most important are the fine structures of diatoms such as Surirella gemma and Amphipleura pellucida or artificial fine divisions as in a Nobert's grating.
The oldest known Diatoms are represented by some specimens found entangled in the spicules of a Liassic sponge, and identified by Rothpletz as species of the recent genus Pyxidicula.
In the plankton sessions we found copepods with their egg sacs, barnacle larve andsome diatoms under the highest magnification.Advertisement
The phytoplankton increase produced by the iron fertilization was dominated by diatoms.
On examination I found some nice clean diatoms, many of them unbroken.
The Center's digital image archive comprises some two hundred images of cleaned diatoms, generated by the site's authors.
Some years ago I examined a smear of metal polish under the microscope and found it contained many diatoms.
Read Frithjof's fascinating Micscape article ' A second look at some well known test diatoms ' where this is discussed.Advertisement
One of the slides showed diatoms from Port Townsend, situated a bit north of Seattle, USA, on the Pacific coast.
The earlier southern experiments showed a preference for pennate diatoms over flagellates.
In the South, diatoms are favored over flagellates, and in the north, centric diatoms over pennate.
We have 5 days of allocated science onboard in which to collect cores of deep sea sediments - made up of beautiful fossil diatoms!
Research projects typically involve interdisciplinary teams where we provide expertise in diatom analysis or the use of isotope ratios in diatom analysis or the use of isotope ratios in diatoms.Advertisement
Vol ut-in occurs in the cytoplasm of various Fungi, Bacteria, Cyanophyceae, diatoms, &c., in the form of minute granules which have a characteristic reaction towards methylene blue (Meyer).
The plankton is divided into (a) the Zoo-plankton (such as the minute crustacea and the eggs and larva of fishes and many other marine animals); and (b) the Phyto-plankton, that is, the minute algae, diatoms, peridinians, some flagellate protozoa, spores of alga, etc. The investigation of the plankton from a new point of view, begun by Hansen in 1889, was continued by Lohmann at Kiel, by Cleve in Sweden, by Gran and Ostenfeldt in Norway and Denmark, and by Herdman, Allen and others in England.
Only the " free " carbonic acid and that of the bicarbonate can be utilized in the process of photosynthesis by the diatoms and alga.
Silica (which is required for the skeletons of diatoms, radiolaria, peridinians, etc.) is present in about the same concentration, but it is now suspected that a source of this substance may be clay washed down from the land and present in the sea in the colloidal form.
Pure water, then, has a hydrogen-ion concentration of io 7 but sea-water gives (because of the mixture of the salts in solution) the concentration 108 ' 2 and when photosynthesis by the larger alga, or diatoms, is very active this figure falls to about 109 ' 1.
The coarser particles of the sediments are deposited near the shore as gravels, sand and muds, but the very fine particles remain in suspension in the colloidal form, and some of this may be acted upon by marine bacteria or (it is surmised) even utilized by diatoms as a source of silica.
The yellow brown stellate colonies are an incredibly beautiful sight and are far better seen freshly collected than cleaned in the manner of diatoms.
The food passes into these lobes, which may be found crowded with diatoms, and without doubt a large part of the digestion is carried on inside the liver.