. Storia naturale. Zoologia. 7i8 protozoi. Non vi è dubbio che Radiolaria abbondava in mari dove il grande Chalk letti erano depositati, non sono stati trovati in Chalk; i loro scheletri siliceoua probabilmente avente stato sciolto e ri-depositato come pietra focaia. Nella successiva divisione dei protozoi, troviamo gli animali in cui il proto- plasmic processi del corpo sono ancora ulteriormente specializzato. Essi non sono più inviare pseudopodi indefinita per creeping lentamente lungo la Flagellata. sulla superficie del terreno, né fanno galleggiare liberamente nell'acqua, il protoplasma streaming su tutti i lati in ammenda ra

• Collaboratore: The Book Worm / Alamy Foto Stock
• ID dell’immagine: RDX6C0
• Dimensioni dei file: 7,2 MB (253,8 KB Download compresso)
• Liberatorie: Modello - no | Proprietà - no
• Dimensioni: 1875 x 1333 px | 31,8 x 22,6 cm | 12,5 x 8,9 inches | 150dpi

Altre informazioni

Questa foto è un'immagine di pubblico dominio, il che significa che il copyright è scaduto o che il titolare del copyright ha rinunciato a tale diritto. Alamy addebita un costo per l'accesso alla copia ad alta risoluzione dell'immagine.

Questa immagine potrebbe avere delle imperfezioni perché è storica o di reportage.

. Natural history. Zoology. 7i8 PROTOZOA. there is little doubt that Radiolaria abounded in the seas where the great Chalk beds were deposited, they are not found in chalk; their siliceoua skeletons probably having been dissolved and re-deposited as flint. In the next division of the Protozoa, we find animals in which the proto- plasmic processes of the body are still further specialised. They no longer send out indefinite pseudopodia for creeping slowly along The Flagellata. on the surface of the ground, nor do they float free in the water, the protoplasm streaming out on all sides in fine rays. We now have only one or two processes adapted for locomotion through the water, and these are long and whip-like. These whips or "flagella, " at the anterior end of the body, by their constant movement, drag it along rapidly through the water. Some of the simplest of these Flagellata are so very like vegetable cells, that they were long excluded from the animal kingdom. It ia, indeed, impossible to draw any very hard and fast line between the lowest plant and animal cells, and, as authorities are still more or less divided in opinion, such simple Flagellates may be regarded as belonging to a border land. One point in which many of the Flagellata resemble vegetable cells is colour. The Protozoa of other divisions are usually colourless and transparent, whereas many Flagellates are of a bright red, yellow, brown, or green. Some of the simplest of these animalcules (Fig. 6, A) as they dart across the microscopic field by the help of their whips, which, on account of the rapidity of their movements are for the time invisible, sparkle like minute emeralds. Some of the red Flagellata, when swarming in great numbers, produce large red patches on the sea. Other forms shine with phosphorescent light, and cause the beautiful glow often seen among the breakers on a shore at night. Thirty thousand animalcules are said to be contained in one cubic inch of such phosphorescent wa

Parole chiave associate all'immagine

• bookauthorly
• bookcentury1800
• bookdecade1890
• booksubjectzoology