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That this precipitation takes place all over the area where the icebergs are breaking up, constantly, and to a considerable extent, is evident from the fact of the soundings being entirely composed of such deposits; for the Diatoms, Globigerinoe, and radiolarians are present on the surface in large numbers; and unless the deposit from the ice were abundant it would soon be covered and masked by a layer of the exuvia of surface organisms."
A tow-net is filled with diatoms in a very short space of time, showing that the floating plant life is many times richer than that of temperate or tropic seas. These diatoms mostly consist of three or four well-known species. In turn they afford food for creatures great and small: the crab-eater or white seal, the penguins, the Antarctic and snowy petrel, and an unknown number of fish.
A few lichens of the species Usnea melanoxanthra sprawled over the black rocks. The whole meager flora of this region consisted of certain microscopic buds, rudimentary diatoms made up of a type of cell positioned between two quartz-rich shells, plus long purple and crimson fucus plants, buoyed by small air bladders and washed up on the coast by the surf.
In the great intermediate zone, occupying some 110° of latitude, which separates the circumpolar Arctic and Antarctic areas of silicious deposit, the Diatoms and Radiolaria of the surface water and the sponges of the bottom do not die out, and, so far as some forms are concerned, do not even appear to diminish in total number; though, on a rough estimate, it would appear that the proportion of Radiolaria to Diatoms is much greater than in the colder seas.
The plant grows rapidly and is endowed with much vitality, for it resists changes of temperature to a remarkable degree. Vaucheria affords a choice hunting ground to the microscopist, for its tangled masses are the home of numberless infusoria, rotifers, and the minuter crustacea, while the filaments more advanced in age are usually thickly incrusted with diatoms.
Transverse section of an Amphioxus-larva, with five gill-clefts, through the middle of the body. The small particles that the Amphioxus takes in with the water infusoria, diatoms, particles of decomposed plants and animals, etc. pass from the gill-crate into the digestive part of the canal, and are used up as food.
The waters of the ocean, all along the borders of the icy barrier, produce in amazing abundance the family of water-plants named Diatomaceae. The Diatoms are so called from their faculty of multiplying themselves indefinitely by splitting into two; and so rapidly is this process performed, that in a month a single diatom may produce a thousand millions.
These plants, called Diatoms, which live both in salt and fresh water, are single cells feeding and growing just like those we took from the water-butt, only that instead of a soft covering they build up a flinty skeleton. They are so small, that many of them must be magnified to fifty times their real size before you can even see them distinctly.
Certain forms of bacilli are known to Science that have been subjected to degrees of heat and cold that are but terms to any but the scientific mind. Low forms of life called Diatoms or "living crystals" are known. They are tiny geometrical forms. They are composed of a tiny drop of plasm, resembling glue, covered by a thin shell of siliceous or sandy material.
Observation 17. Dry land by the side of railroad. Protuberans not abundant. Observation 18. From side of ditch. Filled with mature Geraiasma verdans. Observation 19. Moist earth near a rejected timber of the railroad bridge. Abundance of Gemiasma verdans, Sphaerotheca Diatoms. Observation 20. Scrapings on earth under high grass. Large mature specimens of Gemiasma rubra and verdans. Many small.
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