The Birmingham age-herald., 1924-01-04
..FIRESIDE SCIENCE
The Fresh Water Haunt

If all the rivers. lakes, marshes and fresh water pools we're collected in a single basin, its area would be about as large as that part of the United States lying west of the Mississippi, or, in round numbers. 1,S00,000 square miles.
 tAlthought one of life's smallest haunts, its denfzens; are literally as
 numerous as the stars. There are more microbes, for example. in an al- ligator's wallow than all the man.
 mals on the earth combined. Every
 where fresh water is fresh water, so
 the differences one finds in samples
 entirely from the kind of creatures
 inhabiting those waters The kind of organisms that cause. stagnation in the hot, humid pools Of equatorial Africa could not exist in the ice-cold pools of Alaska, nor in the goblet volcanoes. But wherever the waters are sufficiently warm, innumerable freshwater species find their way into them.
 The lakes of northern Canada freeze solid every winter, and pre- sumably all aquatic creatures perish
 with their eggs, yet when the short.
 hot summer cones water-fleas are found emerging from :; those lakes. How did the eggs get there? If you
 will examine the caked mud on a mi
 gratory water-bird's feet you will find thN answer; or, if you will place
 a particle of that dried mud in glass of warm water, you will presently | lind water-fleas and other forms of | pool organisms emerging from 1t. That the eggs of aquatic creatures can live for a long time in dry soil
 has been proved beyond question. Once naturalist filled a pill box | with mud from the pool of Gibon,
 near the Jaffa Gate, at Jerusalem,
 and forgot about 1t for 40 years.
 Then, finding the pill box among cer-
 tain mislaid souvenirs of his trip, he
 emptied the dust into saucer of
 warm water and produced brood of
 water fleas. The life in the eggs
 had survived 40 years of drouth. In like manner, the life in the eggs laid
 in warm water pools, which dry up
 caked mud at the bottom until the
 water returns. 5t1 l Pasteur proved that no kind of plant or animal organisms can be gen. erated spontaneously; for from pure
 water, sealed in airtight containers,
 no form of life can come. But as soon as water Is exposed to aid the
 notes seen in sunbeams (which are | seeds of life) settle in the water and
 hatch. A tiny particle of dust may | be freighted with the eggs of dozen
 different kinds of bacteria.
 | Fresth water animals have de-
 scended, it is thought, from salt
 water ancestors. We know this is true of cells, crabs and certain kinds of fresh water fishes, because they
 have to go back to the sea to spawn.
 Take the case of the sponge. which was one of the earliest orders of an- imals that acquired many-celled | body-there are hundreds of kinds of sponges, but only one kind lives in fresh water. and 1t thrives best in fresh water, near the mouths of Generation after generation. this particular kind of sponke has ven- tured farther and partner up stream and has practically escaped from the bondage of the sea. The founder, salt water fish, is now learning to live in fresh water, being frequently found at some distance up stream from the sea.
 Directly and indirectly fresh water organisms have interfered with the career of human races. A great and cultured race of Indians, for exam pie. once lived in Central America the ruins of Maya cities show that
 the builders were as capable in many ways as the Egyptians. What be- came of the Mayas? Mosquitoes,
 carrying malaria germs, which some
 how found their way into the sur
 rounding swamps, played a big part
 in the Maya tragedy.
 And why did Greece decline?
 Thomson quotes authorities to the
 effect, that the decline was caused by malaria of this be so," he says, i've
 may link the decline of Greece to the
 mosquito, which harbors and spreads the microscopic animal that causes
 malaria in man."
 In the next article we shall ex-
 plore somewhat deeper into the fresh water haunt.