WONDERS OF THE MICROSCOPE.

New Zealand Herald, Volume XLIX, Issue 15056, 27 July 1912, Page 1 (Supplement)

WONDERS OF THE MICROSCOPE.

NATURE'S JEWELS.

No. 11.

B7 G. A. KAWSON.

The world of life revealed to tip by the microscope is a world of sneh. exquisite and fantastic beauty tfcae at times the ardent student fee!> that he is surely transported into Van fairy-land of his childhood. So delicate, so marvellous, so indescribably beautiful are the forma upon which his enraptured gaze rest«, that ho feels convinced that for the no»ce> he has indeed left this humdrum and prosaic world behind him, and has been permitted to take a peap into the ZLlysian fields. And, perhaps, no objects tend to awaken this sensation more powerfully in the observer than those tiny plants, the diatoms, whose wonderful story we partly considered in a former articlei and which we shall conclude in this.

I have already referred to those marvellously intricate and symmetrical markings, composed of lines and dots, which cover the. flinty surfaces of the diatoms, but I desire to add a few more words on) this point. On some species (such aa Amphipleura pellucida, Pleurosdgna angulatum, actinocyclus, navicula, etc.), these lines and dots are arranged in rows of from 76,000 to 120,000 to the inch! Thus stated, perhaps, these figures do not con-, vey much to the lay mind, but let us endeavour to realise what they signiiy when put somewhat differently. I will ask one of my lady readers to take a single hair of her head in her hand for a moment, and contemplate it. It is pretty thin, is it not? Very well; how, suppose we take this one single hair, and split it lengthwise Unto 400 separate hairs, then take these exceedingly fine strips and place them in between the lines and dots on some of our diatoms, and we should find that they would just fill up the gaps between 400 of these markings, which, remember, run from 76.000 to 120,000 to the inch!

It may appear to some rather paradoxical that the ' diatoms should be plants, and yet be capable of perfectly free movement at the same time. But, as we progress in our studies of minute life, we shall find that many lowly plants are free moving organisms. At one time there was some doubt about the classification of the diatoms, but leading microscopista are now agreed that they are true plants. Their vital and chemical 'processes, and the fact that chlorophyll green colouring matter of plants—is found in their bodies, relegate them beyond a doubt to the vegetable kingdom.

It is a beautiful and an absorbingly interesting sight to watch some living diatoms in a drop of water under the microscope. They glide with a graceful motion in a straight line through the water, and if perchance, they encounter any obstruction in their path, they, never seem;, to attempt "to pass round it, but reverse the motion, and glide back again towards the point whence they came. These movements are apparently effected by the action of very fine ciliathread-like processes, which lash the water with a rapid vibratory motionwhich are so delicate: that they can only be seen under the very highest powers of the microscope. ,i,:,

Diatoms propagate their Mnd* after the manner of all unicellular organisms. That is to say, they increase by. means of celldivision, or fission. They split longitudinally, and each half grows into a complete individual, so that- one becomes two, two become four, four become eight, and so on in geometrical ratio. By this means they multiply at such a prodigious rate that one eminent authority, the late Professor W. Smith, estimates that "no less than a thousand million individuals may be produced by division from a single plant in one month!" , Never for a moment must we lose sight of the fact that these wonderful jewels of Nature are of almost infinitesimal dimensions, the great majority being entirely below the range of normal vision, and, perhaps, we will comprehend this better when we endeavour to realise that the markings on the diatoms can only bo properly brought into view, and all their intricacies studied under the microscope, by employing magnifications so enormous that if they were applied to an object one inch in length they would make that object appear sipcty-e'ight yards long! We have already seen the important part the diatoms play in rock-formation, and, like most things in the economy of Nature, they have a utilitarian aspect as well. Besides serving aa food for myriads of minute Crustacea and micro-organisms, which inhabit our waters, they are distinctly serviceable to man in the form of knife-polish! Very few people, I imagine, are aware that knife-polish, as well as that toothpowder known as " Zozodont," are simply diatomaceous earths, and that in a small tin of this substance, which can be purchased for a few pence, there are countless millions of some of Nature's most exquisite sculpturings. The diversity of these plants is truly astounding. There are thousands of species of diatoms, of all imaginable shapes, but all agreeing in' structure and in their modes of propagation. While the great majority of the diatoms wander about singly in the water, others become embedded in various kinds of floculent vegetable matter, while others again are more socially inclined, and live in groups or clusters. They produce long filamentous foot-stalks, by means of which they attach themselves to the stems of all kinds of aquatio plants, both fresh-water and marine. Their movements are therefore restricted to waving about on their stems in the water. All the year round diatoms may be collected, but in spring and summer they are most E abundant. . In warm, sunny weather they may be found floating in myriads on the surface of green ponds, for, after the fashion of all vegetable life, they absorb carbonic acid and give off oxygen during sunlight, and this causes them to become buoyant . and rise ;to . the surface. For microscopic examination, that is,to say, if the markings are to be studied successfully, the gatherings must be rinsed in water, to which a little acid has been added. If this is done carefully they can be obtained in a fairly clean condition. But to separate the diatoms from the other material contained in the sediment is a delicate, as well as a long and somewhat tedious process, which can only be carried out under the microscope. The most convenient appliance for moving them is a bristle inserted in a handle.

In their Jiving state diatoms are usually of a brownish or greenish-brown colour, owing to the minute granules of chemical substances contained within the protoplasm of their bodies. To sum. up : Just let us think what all this means. Consider, as one charming writer thus expresses it, these "complex designs involving the symmetrical arrangement of many thousands of lines and dots on a speck of flint that is too small to be seen without a microscope! The seven artificially-constructed wonders of the world, whatever they may be, are nob to be compared with these marvels of regularity and exquisite beauty And further, in the words of another skilled microscopist: " The perfection and variety of these patterns are truly marvellous when we bear in mind how minute are the organisms which have manufactured them. If -we try to realise this fact we shall have something that will test our thinking powers, and that may induce us to take a deeper interest in Nature study." In my next article I shall describe one of the greatest marvels, as well as one of the most beautiful object:? of. the microscopic world—a veritable macrocosm within a microcosmnamely, that wonderfu| jjlant known as .Yolvox . Glpbator. ""**•