Parents are Essential

New Zealand Listener, Volume 3, Issue 57, 26 July 1940, Page 8

Parents are Essential

HERE certainly were some extraordinary ideas in the old days. One was that frogs and reptiles could be produced out of mud and slime. These old ideas die hard. For hundreds of years it was thought that a swarm of maggots that appears when anything is left to decay was directly generated from the putrefying material. Some of the flies produced in this way were mistaken for bees, and Virgil even gives directions for producing swarms of bees from the carcass of a dead ox. As soon as people really began to look at animals, it became obvious that these flies and similar creatures were hatched from eggs which their parents could be seen laying. If no eggs were laid, no maggots appeared. When the microscope was invented, however, it disclosed countless numbers of minute animals, and these did seem to appear spontaneously in suitable materials. For instance, soup soon goes bad if exposed to the air for several days, and is then seen to contain vast numbers of living things. But Pasteur was able

to prove that even in such cases spontaneous generation had not occurred. He took soup and thoroughly sterilised it by boiling, so that no living things could be present in it. Then he sealed it up so that no microbes or their spores could get in from the air, When this was done the soup did not go bad, however long it was kept, but as soon as it was opened it went bad in the usual way. The whole of the huge tinned-food industry depends on this fact. But, to answer the question about the truth of spontaneous generation. It has been shown that it does not take place even among the smallest and simplest animals which we can see. There are, however, still smaller living things, too small to be seen even with the most powerful microscope. The idea of spontaneous generation has not yet been disproved as far as these are concerned, but from everything we know at present it seems to be very unlikely that living things ever arise nowadays except from living parents. (From "Growth and Development of Animals"-Miss M. L. Fyfe and Professor B. iP Marples, 4YA, July 9.)