IN TOUCH WITH NATURE

Otago Witness, Issue 4048, 13 October 1931, Page 67

IN TOUCH WITH NATURE

By

EARLY ROCKS.

J. Drummond, F.L.S., F.Z.S.

In rocks, in New Zealand, Europe, and North America, there occur fossils of the same species of marine creatures, evidence that there was free intercommunication in the wide Silurian seas. They rolled over a large part of Europe and North America. They lapped a vast southern continent, of which Asia. Australia, and most of Africa were a part. They'seem to have been mainly shallow seas, thickly populated with lowly creatures, some extraordinarily beautiful in structure. There were minute creatures, jelly-like, devoid of definite organs, but secreting horny shells, or cementing together grains of sand that made protective shells.

Sponges lived in those seas in prodigious numbers. Stone-lilies were so plentiful on the sea floors that their remains form solid beds of limestone, hundreds of feet thick and covering thousands of square miles. Starfishes and brittle-stars are preserved in Silurian rocks in their natural positions as they lived. Tracks and burrows in the rocks were made by ancient sea worms. The chambered Nautilus has persisted through the greater part of the vast geological time from the Silurian Period to this dav. It now is the only representative of the old chambered cephalopods that once were remarkably abundant.

The trilobites achieved their highest development in the Silurian. The decline, fall, and extirpation of these ancient crus--taeeans was more than compensated for by tlie rise, late in the Silurian Period, ot almost equally remarkable crustaceans of amazing size, some of them six feet IjW- ■ •Among fossils in the masses of Silurian rocks in New Zealand are many trilobites, corals, and brachiopods. It is species of these that link the Silurian marine life of New Zealand with the marine Silures of Europe and North America. Strangely. New Zealand’s Silures are markedly unlike those of Australia. Professor J. Park, of Dunedin, explains this by the theory that there was a contmuoiis littoral between New Zealand America, and North-west Europe, while between New Zealand and Australia there was deep sea, or a land barrier.

Sand and mud, washed into the seas piled up. Occasionally the floors of the seas were raised. The waters advanced and retired again and again. When the Silurian Period was far spent there were signs of greater change. The earth's crust heaved, mountains arose from the seas, oceans contracted, and continents. Y ei ’i e u a]l the tini e, as Sir Ai chibald Geikie stated, generations of cieatures of the sea came and went in a lo n g procession, leaving their remains in the ooze at the bottom.

rocks are called Silurian from tlie Silures, a tribe of ancient Britons pho lived on the border of England and Wales where strata of that age are particularly well developed. The name is used ad over the world for strata that contain the same kind of fossils. Siluiian fossil plants are few and meagre. mos t l Y sea weeds; but on land lj copods.or club mosses, and ferns were the chief plant types. In. the Carboniferous Period, which followed much later, they reached a higher development. Sir Archibald Geikie, in his profound studies saw dnnly Silurian lands with waving thickets of fern. Above them, Ivcopod trees raised fluted and scarred stems, threw out scaly moss-like branches, and h,! cl spiky cones. There were no flowers, the picture is a dismal one, but it should « t! ; at world’s childhood as not blight. In the Silurian Period it nas in its early infancy.

The colours of flounders are nroduced by pigments in cells distributed in the skin, borne cells contain a blackish-brown pigment otners pigment of different shades from deep red to pale yellow; others are opaque white. Most of the colour patterns are produced by the distribution of the cells. Recent tmiis in England seem to show that dark patches, orange and black spots, and white spots distributed in a particular wav are ancestral patterns, and that species which wear them are in most cases closely adapted to their environment in the Y- a l cr ’ a * acu Jty they have inhei’ited from distant ancestors. Pale spots and patches probably are of recent evolution, and may represent recent reactions by their wearers to particular environments.

Plants have an intolerable thirst. Failing always to satiate it, they are for ever thirsty. Watery solutions rise frpm the roots to the leaves, where most of the liquid goes into the air as water-vapour Only a small fraction of the water that moves rapidly up in the woody conduits of stems is held in chemical combinations in a plant’s cells. This movement of ascending liquid is as important to a plant as the circulation of the blood is to a human being. Water is raised from rootlets deep in the soil to the tops of trees, perhaps 400 feet high, by power generated by the sun, each plant bein<' a sun-driven factory. Dr D. T. MaeDougal, of the Desert Laboratory, Tucson, Arizona, explains this power system in an article in the August number of the Scientific Monthly, published by the Science Press, New York. The number has eight or nine other articles, all very interesting and informative.

For no obvious reason, albinism Is a marked character in New Zealand birds. Almost every native species has had albinos. This is so even in the kiwis. Their plumage is peculiarly soft and hairlike, and an albino kiwi is symbolic of purity. Amongst introduced birds, white sparrows, skylarks, and blackbirds are not very uncommon. The albinism often is only partial. Mr A. Cowan, Rewa-rewa. North Island, while riding.along a littleused back road near Otorohanga, saw a white bird flittering about in the scrub. On watching it. closely, he was surprised to find that it was a tom-tit. He had seen and heard of albinos in other species, but that was his first acquaintance with an albino tom-tit.

Pieces of timber, tunnelled, chambered and honeycombed, sent by a Wnangarei resident, illustrate the way in ■which white ants, which are not ants, but termites, work mischief earnestly. Social in disposition, they live in colonies and eat wood, destroying buildings and ridges, and •making themselves a menace to property. Apart from this, they excite endless surprise by their admirable, grovelling, md abominable practices. Some of these are too unpleasant to be described in a newspaper. On the other hand, thev are industrious, courageous, self-sacrificing; and highly intelligent, observing strict and complex social laws. In every community or termites there are workers and soldiers. Armed with large heads and powerful jaws, the soldiers go forth ■valiantly to meet foes that threaten the community. At the head of each community are a royal pair. The queen ranks as one of the most remarkable insects in the world. She is carefully guarded by the workers and protected by the soldiers. At the same time, the government is democratic, not monarchical. The queen's actions are regulated by the workers. The whole community is under their control. : In spite of the pre.-eme of royalties, the | industrial system is socialistic, not individualistic. each member sinking its nidi I viduality in the whole community. TerI mites are called white ants popularly beI cause their habits, in some respects, are i like the habits of ants, but their comI munities differ greatly from ants’ comi munities; and an English entomologist has I stated that they differ in structure from I ants as widely as beavers differ from men.

W hiie many insects are robbers, burglars. and bandits, systematically defrauding and slaying other sorts of insects, the association of some insects with other insects ,may be quite honest and honourable 1 ' 1 P 3 38 tl3f * . case species of small beetles, aphids, and scale-insects that live with ants or supply them with dainties in the form of sweet secretions Many insects are parasites on other in sects, but merely feed at their hosts’ expense instead of taking their lives. Some gall-flies never make galls. They lay their eggs in galls made by other insects, tlieir 5 oung finding the ready-made galls comfortable temporary homes. All in-ects that follow these practices are called inquilines, or, commonly, cuckoo-parasites, their system resembling the notorious system of cuckoos, which use nests made by other birds. Bees and wa<ps receive the attention of inquilines that eat stored honey, devour the honeycomb, or willingly act as scavengers.