The Mendelian Theory

New Zealand Tablet, 12 August 1909, Page 1251

The Mendelian Theory

It will interest our readers, especially those engaged in agriculture, to know that < extensive experiments have been carried out in England in recent yqars with the object of improving the grain crops, especially wheat. - Professor Bateson, of Cambridge, is working most assiduously in this direction, his experiments being based on what is known as Mendelism. The result (says the Catholic Weekly) has been that what was formerly a game of chance played between man and plants has now become something of an exact science. Mendel was a Catholic priest of Silesia, in Austria. He was born in the year 1822 and died in 1884, and thus was contemporary with Darwin and Wallace. At the age of 21 .he joined the Augustinian Monastery of K6nigenklos : ter, at :Altbriinn. His ability as a teacher marked him* out for special attention. He went to Vienna for an extra - course of studies, then returned to his monastery, where he taught and carried out his experiments. Being the son of a farmer, he had from childhood possessed the taste and opportunities for . the botanical studies which afterwards made him so famous. During the last sixteen years of his life he held the office of Abbot, the duties of which seem to have put an end to his scientific work. What He Discovered!.

By experimenting in the cross-fertilisation of plants, Mendel discovered two great laws of heredity. His chief experiments were with peas. Taking two races, the tall and the dwarf, he found that the first .generation of hybrids were all tall. But when these hybrids in their turn were* sown, the resulting plants were mixed, some being tall 'and some dwarfs ; and they were mixed in definite proportions, three tall specimens for every one dwarf. To the quality which appears in the children of the first parents is given the name of ' dominant,' whilst to the quality which disappears in the children, but reappears in the grandchildren, is given the name of ' recessive.' Similar experiments have been' made with mice. The Japanese waltzing mouse is one that will spend most of its time running round after its tail. This peculiarity it , due to a malformation of an organ connected with the internal ear, which has to do with the balancing power. Now, if a normal mouse be crossed' with a waltzer the children will be all normal, but the grandchildren will be normal and waltzers in the proportion of three to one. The normal organ acts as a 'dominant,' the malformed organ as a ' recessive.' The first law, then, is this: when two races, possessing two antagonistic peculiarities, are crossed, the hybrid exhibits only one, and as regards this character the hybrid is indistinguishable from its parent.

There are no intermediate conditions. The second law is that in the formation of the pollen or egg-cell the two antagonistic peculiarities are segregated, so that each ripe germ-cell carries either one or other of these peculiarities, but not both.

Of course, the above is only a rough statement of the main idea, which is quite easy to understand. Indeed, anyone having a. small garden may make the experiment and verify the laws. Its bearing on the question of Darwinism is also easy to understand. This is its importance from a scientific point of view — it makes the theory of natural selection look very small. Some eminent scientists declare that it has finished it altogether. Darwin believed that development was continuous, whereas Mendel has shown it to be discontinuous. There is discontinuity in inheritance as well as in variation.

Its Practical Value.

So far the practical value of the theory has been mostly observed in agriculture. The farmer with its aid can obtain a pure stock much more easily than hitherto. Wheat is now being produced on land that previously was quite unsuitable. The quality of the wheat itself is also being improved so as to meet the competition of Canada, the United States, Russia, and other countries. There is quite a number of lessons to be drawn from the little history of Mendelism. It shows us first that science not only can, but does, flourish in the Catholic Church. It teaches us, secondly, to be prudent with regard to scientific hypotheses. The echoes of the brazen tumpets which told of the triumph of evolution and decline of religion can now scarcely be heard ; and as ' natural selection ' and ' survival of the fittest ' were words to conjure with in the past, so ' dominant ' and ' recessive ' will be words to conjure with in the future. It teaches us, thirdly, to be humble with our pet opinions. It was not until fifteen years after his death that Gregor Johann Mendel was discovered. For at least eighteen years of his lifetime he knew his own theory, and must have seen the contrast between it and evolution. Now he, or, rather, mankind, enters into the reward of his labors. He is proclaimed the hero of the most absorbing problem of modern biology.