Simplest Life

The basic difference between the quick & the dead is ability to grow. Biologists feel that if they could understand growth, they might understand what life is. But growth in nature is complicated. Within a growing cell are hundreds, probably thousands of chemical compounds, their molecules weaving in & out, exchanging atoms and energy. Like a nation, the cell imports (absorbs), exports (excretes), and is influenced by its environment: the innumerable chemical substances in the plant or animal juices outside its frontiers.

To study the growth of such a cell is difficult; it involves too many factors. So forward-looking biologists are trying to reduce cell growth to simplest terms. One of these simplifiers is British-born Professor Kenneth Vivian Thimann of Harvard. Last week, in an air-conditioned room (hot and humid), he was sprouting oat kernels in total darkness, observing them in dim red light.

Controlled Growth. After a few days, the seedlings have ghost-white roots and little white spikes (the coleoptiles) which envelop the embryo leaves. Thimann cuts off the coleoptiles, trims their points, and strings the tiny hollow cylinders on the hairlike teeth of a comb. Then he puts them in water containing a little sugar and indoleacetic acid (a growth-promoting substance). He measures them under a microscope and tucks them away in darkness.

The cells grow for a day or so, "eating" the sugar and acid. They grow in isolation, uninfluenced by the complex substances which would normally reach them from the oat seed. Professor Thimann can experiment on them, and know what he is doing.

One recent experiment was to put a "growth inhibitor" (iodoacetic acid) in the water. It did not kill the cells, but stopped their growth by breaking a necessary chain of chemical reactions. Then, one after another, Thimann added likely compounds, hoping to see growth start again. He found that malic acid (which is found in apples) would overbalance the evil influence of iodoacetic acid, allowing the cells to grow. This proved that malic acid was somehow involved in the chain of reactions which the inhibitor had broken.

It was not an important discovery, but, jotted down in a book with a thousand others, it might help eventually to explain what life is.

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