Old Salt Lake | Virtual Museum
______ 1907, "Diatoms", By Miss Sarah P Monks ______
Bulletin - Southern California Academy of Sciences, Volumes 6-9, 1907
Southern California Academy of Sciences
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"Figure 1, Arachnoidiscus and Figure 2, Aulocodiscus are round fossil forms from Redondo Beach and they show something of the pattern and arrangement of projections."
[ Transcription - full text of 1907 paper, "Diatoms", by Miss Sarah P Monks ]
Diatoms are organisms that have characteristics of both plants and animals. Unlike other plants they have the power of voluntary motion and unlike most animals they possess chlorophyll. They are microscopic.
Zoologists look at them askance and botanists do not want them but they are the pets of the microscopist and well theydeserve this honor for they are among the most exquisitely beautiful objects of the world.
They, unlike plants, have a silica shell composed of two valves one fitting over the other like the lid of a pill box These glassy valves are decorated with knobs points and stria arranged in the most varied and delicate tracery. Sometimes under a low micro power diatoms appear changeable blue green and various colors because their tiny projections break the white light into its rainbow tints.
Diatoms are at present classed as brown alga or sea weeds on account of the dark brown pigment under their siliceous shell.
An interesting fact in regard to color was noticed by the Russian diatomologist C Mereschowsky among the recent diatoms of San Pedro It was a species of diatom without color It moved acted and lived like a diatom was a navicula but had no brown pigment no chloraptyll and sailed as a phantom among its fellows.
M. Mereschowsky explained it thus Living among the waste of the fish cannery surrounded by an abundance of nutrient material a sort of predigested breakfast food this spectre of a diatom not using its chloroptyll to manufacture its dinner had lost the chloroptyll just as do the parasites among its kinsmen of the higher plants.
Diatoms vary indefinitely in shape Some are round others oval squarish triangular elliptical rod like or boat shaped. One kind Isthmia very abundant on Pacific algie looks like a fat little money wallet with a decorated strap buckled around to keep in its valuable contents Salt water has more of the round or roundish kind and the long forms are more common in the fresh water. Figure 1 Arachnoidiscus and Figure 2 Aulocodiscus are round fossil forms from Redondo Beach and they show something of the pattern and arrangement of projections Figure 3 is an artificial arrangement of eleven This kind breaks up the white light and under a low power objective with the slightest motion change color and glow like the slumbering hues and fire of jewels.
Figure 4 gives an idea of the variety of size and form of diatoms.
Diatoms are found singly or in colonies free or attached in hot or cold fresh or salt water recent or fossil all over the world Their motion is deliberate in marked contract with the irritable impatience of the Infusoria which are their pond companions. One boat shaped diatom called Navicula of which there are two or three hundred species is so abundant in all fresh water pools and ponds that nearly every microscopic mount shows a quantity of specimens and often several species.
several species These fairy brown fleets go moving across the field sailless and rudderless with a steady and gracefully easy motion If perchance one meets with an obstruction a bit of alga fibre of wood or grain of earth it bumps against it obstinately several times then convinced that its Northwest passage is blocked it backs off and sails backward with equally deliberate dignity.
One odd species is called Bacillaria paradoxa Its motion is most peculiar. This Bacillaria is composed of numerous rod like pieces that can move upon each other and it has the power of attaching itself to objects. Slowly across the field may be seen extending a jointed rod its parts sliding past each other like a sliding ruler till it attains its full length Then the pieces slide backward and an arch or zig zag figure or pontoon bridge is formed the arrangement varying constantly with the ceaseless motion till one is weary of watching. This peculiar species was abundant on Flower street back of the State Normal School before its ocean was drained and dried up for the good of the public.
The siliceous shells of diatoms are practically indestructible and consequently they are an important item in world building. They are found in all geological strata as far back as the Devonian and probably much of the amaphous silica of the Silurian Age was at one time diatom shells The fossil deposits are called diatomaceous earth.
Abundance of Diatoms
These plants must have existed formerly in inconceivable numbers for their remains form extensive beds of miles in extent in almost every country of the world.
The earth is abundant in California and all states of recent geologic formation. The city of Richmond Va is built on such a deposite from two to eighty feet thick and several miles in extent. The city of Los Angeles has its share There is a large area of this earth under the court house another at Second street and Bunker Hill avenue another on Flower street between Second and Fourth streets In fact there is scarcely an outcrop or a street cutting in this city that does not show some diatomaceous earth. The forms however of Los Angeles diatoms are not rare or remarkable A large Coscinodiscus is extremely common.
The most extensive deposits in this locality is at Redondo Beach about two miles from the city. Here the entire bluff about eighty feet high and at least a quarter of a mile on the sea front is composed of diatomaceous earth As a similar deposit crops out five miles back from the sea in all probability they are continuous Here the earth is of all conditionss and colors soft friable in loose thin layers white compact yellows brown almost black. Like all the Coast bluffs this place shows a surface of pinnacles abrupt fronts huge masses that have loosened and slid part way down and debris of all sizes at the base but all here is of unmixed diatomaceous earth. Throughout this deposit there are flinty masses looking like petrified wood which are supposed to be metamorphic diatom remains. It is called Diatomite Specimens from Redondo have been distributed all over the world and the locality is famous for richness in forms and number of specimens. Unlike chalk or clay which it somewhat resembles this earth is of extremely light weight.
The compact varieties float At Redondo sometimes rounded pieces from the size of a marble to lumps a foot across are strewn on the beach for a mile or more where they have been washed ashore after floating and being rolled about by the waves It is possible that the famous floating find of a number of years ago that was caught by fishermen off Santa Monica was a bit of flotsam from the Redondo quarry This piece was unique in number of species and is one of the most famous lumps of the world Its resting place before it began its voyage is unknown and regrettable and is as fondly sought as a lost mine.
Their Beauty Under the Microscope
Diatoms have been used for a long time as tests of the power of objectives because of the variety and symmetry of their designs and the great range of size.
One cannot consider diatoms without admiring the skill of miscropists who mount them and it is a question of which excites the most admiration the marvelous beauty of these plants or the rare dexterity of the scientists. Indeed the compositions of E Thuin of Leipsie are so surprisingly won Jarful that they are called the Oh my slides. The diatoms are made into what is called Type plates where from 100 to 150 forms are arranged in symmetrical rows in a square or they are made into concentric order or fancy designs of vases fountains of bouquets of flowers all well within the scope of a one one half inch objective. In fact the whole figure is so small that to the naked eye it appears as a mere blue on the cover glass And the deft way it is done adds to one's admiration. The earth is cleaned from fragments and sponge specules and the different species sorted out under a microscope all requiring great care and delicacy of touch. Then the diatoms are picked up one by one and put in their places in Canada balsam on the slide then covered and laid away to dry. The lifting and placing is done by an instrument called the mechanical finger which is made to move up and down from side to side by means of screws But the funny thing about it is that the tip of this finger is made of a cat's whisker Nothing has been found to be such a good diatom lifter as pussy's whisker
When one is bitten by the diatom craze the only hope is a microscope and long delightful tramps with dip net and bottles or hammer and basket for possible forms.
Each pool and brook is a treasure land or water and the sun baked street or railroad cuttings become wondrous mines; and His Majesty who delights in idle hands, will have an uncomfortable quarter of an hour when the evening or holiday brings time for a micro hunt among the treasures collected from the pools or the great white earth deposits.
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