NATURE NOTES.

New Zealand Herald, Volume LXVII, Issue 20620, 19 July 1930, Page 1 (Supplement)

NATURE NOTES.

GREAT ARTIFICERS.

HY J. DRUMMOND, F.L. 8., T. 7.. P.

Countless billions of diminutive aquatic plants of a low type, almost invisible to the naked eye, swarming in the sunlit surface of the oceans, amaze men of science by the variety and grace of their form and by the complexity, delicacy, and exquisite beauty of their manifold designs. They are so small that at least ICO of them would be required to rover the space occupied by a pin's head. In some oceans beneath one acre of the surface there are at least five tons and ahalf of these little plants, called diatoms. They are the basic food supply of the creatures of the sea. Oysters, which are dainty feeders, depend largely on them. They are the food of smaller creatures, which in turn are eaten by fishc3 and other larger creatures. To some extent, indirectly, man depends on this pasturage of the sea. For their part, their whole bodies are bathed in sea-water, and from it they draw nourishing salts that are in solution. Being plants, they must come nndor the benevolent influence of the sun. They do n'ot live in the dark abyssmal ocean depths. They make protective shells of material that looks like spun glass. Theso are two structures, like lids, one fitting into the other, and enclosing the body of each plant in a little box. In spite of tho diatoms' delicacy, their shells are indestructable. Tho plants' lives are very short. They multiply rapidly, but die in a few days. Their glassy encasements then fall to tho bottom, forming deposits of ooze, which pile up as the vast ages pass, and, in m?ny places, is raised above the level of the ocean, to excite the wonder and admiration of microscopists.

The shells of diatoms are more beautiful than anything else the microscope has revealed. Their twofold beauty lies first in their form, called their architecture, and. secondly, in their ornamental patterns, called, their sculpture. These beauties were among the first things that amazed men when, 100 years ago, the improved compound microscope gave glimpses into worlds of small things. Wealthy men in England were so charmed with the diatoms that they paid large sums for more powerful and precise lenses in order that studies of the diatoms might be carried further. Diatoms were used as the standard for testing the quality of a microscope. They are so used to this day.

The discovery that diatoms are the basic food of all animal life in the sea has directed attention of their economic importance for 20 years or more. A recunt display at the annual exhibition of the Carnegie Institution of Washington to illustrate the artistic principle in diatoms has drawn attention to the fact that they surpass all other living things in diversity and elegance of form and that they are- inspiration for ornamental designing. As described by an admirer of the diatoms, who saw the Washington dispiay, the surfaces of the shells of many species are covered with polished bars, straight or curved. Others are adorned with beads, in clusters or in parallel rows, straight, curved or undulating. Others have delicate dusty particles or dots symmetrically arranged. Others have feathery, plume-like tracery, like frostwork on a window pane. One of the commonest ornamental devices used by a large group is to cover the surface of the shell with a six-sided network of fine lines, like a delicate fdm of lace. This network sometimes is underlaid with delicate beading; in some cases a single large polished bead is placed in the centre of each hexagonal opening of the network.

All this is very wonderful, but not as wonderful as the fact that this art is produced by a plant microscopically small, composed of a single cell. There is no multiplicity of living cells. " Here are operating," Dr. A. Alann, who conducted the exhibition of diatoms, states in an article in Discovery, " the machinery, the physics, the chemistry, of this master artificer, which takes from tlio water in which it lives a scanty supply of silica and moulds and fashions it into the bewildering forms of beauty that have made if famous. That the laws of the sciences mentioned are operative in the laboratory is unquestionable, but that this chemistry is diatom chemistry, and not human chemistry, diatom physics and not human physics, is equally unquestionable. It is well for the aesthetic student of diatoms to hold fast to this point, which is in danger of being swept into forgetfulness by the tide of magnificent discoveries the chemist and the physicist are bringing to our knowledge."

Another thing that astounds Dr. Mann is the perfect control this living plant exercises over the raw material out of which it builds its wonderful palaces. It shows no trace of subordination to matter. The snow-crystal, a rival of the diatom in beauty, is bound and fettered in its designing by the 'laws of the substance of which it is composed. Water crystalises in only a definite geometrical way, and the ice-crystal or the snowflake must be built on the plan of three or a multiple of three. All its lines must be straight, never curving, all its subdivisions or branches must shoot out at a given angle. The diatom handles its raw silica as a sculptor handles his day, moulding and fashioning it into hereditary forms and fantasies.

Hpw a single cell can produce these results, ts to Dr. Mann, a mystery, and it must long remain a mystery. In jftldition to this, a cell, if interfered with by outside forces, can make two hereditary designs, half a cell, apparently having the same power as the whole. Further than this, one-sixth of a single "cell produced the whole intricate design favoured by the species to which (he cell belonged. About 8000 species of diatoms are known. The wide diversity |in their designs is remarkable. Among them is almost every shape that combines grace of outline and symmetry of parts. There are curved outlines, perfect circles of many sizes, ovals, crescents, serpentines, the letter S, and almost innumerable variations. In the angular forms there are some with two, three four, five, six and up to 20 angles, [ho sides between the angles straight convex, concave, or sinuous. Al " c so accurately proportioned, and so faultlessly done that "tlicy are the delight and tho despair of any artisan who tries to copy them, whether for wall decoration, jewellery, designs, textile patterns, or other purposes." The diatom s name should be pronounced dia-tom, not diatom. It does not mean two atoms. It is composed of two Greek words: ' Dia, through, and " tome," a cutting, referring to loosely connected chains often formed by diatoms.