Design in Nature
Bacteria Make Their Own Compasses
Dr. Richard Blakemore was surveying sediments in a dish and noticed that bacteria in one sample gathered at one side of the dish. He rotated the dish. The bacteria swam back to the same area—the north side of the dish. He placed a small magnet on the south side of the dish. The bacteria collected there. Wherever he moved the magnet, there the bacteria gathered.
Dr. Richard Frankel of MIT joined Dr. Blakemore, and together they discovered by chemical analysis that these bacteria contained 10 times the amount of iron normally found in bacteria. Furthermore, the iron was present as magnetite—a permanent-magnet material at room temperature. When electron-microscope pictures of a bacterium were taken, they showed a line of 22 to 25 magnetite particles stretched lengthwise inside the bacterium. The north-seeking pole of this bar magnet is at the opposite end of the organism’s whiplike strands that propel it. That’s why they always swim north.
Another startling discovery: each bit of magnetite is about 0.05 micron long, and only magnetite particles of this approximate size possess the magnetic properties needed to make a good compass! Just another one of the millions of coincidences postulated by evolutionary scientists? Rather, it’s just another of the millions of evidences of design by an intelligent Creator.
But does their built-in compass serve a purpose? Dr. Frankel said that the magnetic field is felt both horizontally and vertically through the earth. This means, then, that in the northern hemisphere where these bacteria were found, north also means down. These bacteria are too small to distinguish from gravitational pull in water which directions are up and down. So this compass that points them down directs them to the muddy bottom sediments they prefer.
Is this discovery a key to the age-old mystery of navigational feats performed by many animals? For a long time many investigators have suspected that some animals use the earth’s magnetic field to perform their feats. Experiments have confirmed this in the case of pigeons, and recently researchers have found magnetite in the heads of pigeons. Also, they have discovered it in the abdomens of bees. And who knows where else it will turn up?
Human inventors may have the patents on compasses, but thousands of years earlier they were being made by the billions by one-celled bacteria!
Why Onions Make You Cry
When onions are sliced, an organic compound of sulphur is given off. Dissolved in water, it becomes sulphuric acid. So when this compound of sulphur gets into your eyes and dissolves in the moisture there, you have sulphuric acid produced. The old folk prescription for avoiding this: slice your onions under water. Then the acid is manufactured in the water, not your eyes.
Plants That Manufacture Insect Repellents
When insects detect anything like sugar they react as many people—they start to eat! But the plant Ajugara remota foils this urge to eat by its own special chemical compound, ajugarin-1. It blocks the insect’s receptor sites and eliminates its desire to munch on Ajugara remota. This chemical is just one of many anti-feedant compounds found among many members of the plant world. Some anti-feedants repel a broad range of insects; others spoil the appetites of only a single species. All are nonpoisonous.
Scientists are trying to make anti-feedants in their laboratories to repel crop-eating insects. Perhaps next they can make anti-feedants that will turn off sugar-hungry humans.