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MENDEL

himself in teaching until 1851, when he was sent, for a two j'ears' course of study in mathematics, physics, and the natural sciences, to the University of Vienna. When this course terminated, in 185.3, he returned to his abbey, and was appointed a teacher, principally of physics, in the Realschule. He con- tinued in this position for fifteen years and appears to have been genuinely devoted to teaching and to have gained the reputation of being extraordinarily suc- cessful in interesting his pupils in their work. In 1868 he was obliged to relinquish his educational labours on assuming the position of abbot of his monastery, to which office he was then elected.

When appointed to this important post, Mendel, al- ready much engrossed with his biological experiments, hoped that he might have more time for his researches than was possible in the midst of his labours at the Realschule. But this was not to be. The juris- diction and privileges of the abbey are somewhat extensive, and its abbot must, in ordinary times, find himself with plenty of occupation. Mendel, however, in addition to the multiplicity of his duties as abbot, became involved in a lengthy controversy with the Government which absorbed his attention and em- bittered the last years of his life. The Government had imposed special taxes on religious houses, and these Mendel refused to pay, alleging that, as all citizens were, or should be, equal in the eye of the law, it was unjust to ask one kind of institution to pay a tax from which another kind was free. At the commencement of the struggle several other monaster- ies sided with him, but one by one they submitted, until at last Mendel was left alone in his opposition to the tax. Great efforts were made to induce him to yield but he refused, and even allowed the goods of the abbey to be distrained upon rather than sub- mit. In the end — though not till after Mendel's death — the obnoxious tax was repealed. The result of all this strain, as may easily be understood, was a complete cessation in Mendel's scientific work. His appointment as abbot may have been an ex- cellent thing for the monastery, but it cannot be denied that it was a great misfortune for science. The latter years of his life were rendered unhappy, not only by constant strife with the Government, and by the racial controversies which tore that part of Austria at the time in question, but also by constant ill-health due to the chronic nephritis of which he ultimately died. The result of these various troubles was to change that sunny cheerful nature, which had secured Mendel many friends, into a somewhat mo- ro.se disposition and suspicious attitude of mind. A public monument to his memory was imveiled at Briinn, 2 October, 1910.

Mendel's experiments, on which his fame rests, were commenced while he was still a novice, and car- ried out in the large gardens attached to his mon- astery. Dissatisfied with the Darwinian views, then commencing to be known, he undertook a series of experiments on peas which occupied his spare time for eight years. The results of these observations were published in the "Transactions" of the Briinn Natm-al History Society in 1866, and a further paper on Hieracium appeared in the same periodical in 1869. Two short papers of less importance were published during the period of study at Vienna, and this seems to complete the list of the communica- tions which he gave to the world, with the exception of his annual meteorological records, also published by the same society. It is, however, known that he devoted himself to various lines of investigation, bestowing much labour on the heredity of bees. He collected queen bees of all attainable races, European, Egyptian, and American, and made many crosses between the various races. Unfortunately, the notes which he is known to have made on this subject have completely disappeared, and it is not

impossible that he may have destroyed them himself in some of the dark hours which he wa^ called upon to endure during the last years of his life.

The Brunu Society was not a wholly unloiown organization, but its Journal was scarcely one which could be expected to give the widest publicity to a new discovery or theory. It is perhaps largely on this account that Mendel's views seemed for a third of a century to have been still-born. Bateson, how- ever, thinks that this would not so long have delayed his recognition, but that "the cause is imquestion- ably to be found in that neglect of the experimental study of the problem of Species which supervened on the general acceptance of the Darwinian doctrines", and Bateson 's opinion, as that of the man who has done more than any other to make Mendel's views known, is worthy of all consideration. Whatever may have been the cause, the fact remains that Mendel's work was imrecognized imtil, in 1899, three men of science — de Vries in Holland, Correns in Germany, and Tschermak in Austria — almost simultaneously called attention to his publications and started the interest in his line of investigations which has steadily continued to grow and increase since that date. Mendel himself, though grievously disappointed at the neglect of his views, never lost confidence in them, and was wont to exclaim to his friends, "Meine Zeit wird schon kommen". He was abundantly justified in his belief.

It now remains to give .some account of the theory put forward by Mendel and the influence of his work during the past ten years. Mendel liimself confined his experiments to plants, and his most important observations were made on the garden pea, Pisum satiimm. Later observers have dealt, not only with a number of other members of the vegetable kingdom, but also with a variety of animals, using that word in the widest possible sense. With the details of their publications it is not possible here to deal, but a short account of Mendel's own work will suffice to show the lines of his theory. He did not, as others had done and have since done, direct his attention to the entire group of characteristics making up the indi- vidual, but concentrated his attention on certain pairs of opposed features observable in certain plants. In the case of the pea, he observed that some were tall, some dwarf in habit; some had round seeds, others wrinkled; some had green endosperm, others yellow. For the purpose of his own observations he selected seven such characters and studied their be- haviour under hybridization. From what occurred he was led to believe that the progeny of the various crosses behaved in regard to these characters, not in a haphazard manner, but in one which was reducible to the terms of a so-called "Natural Law". One instance given by Bateson will explain what happens: there are tall and short (or "Cupid") sweet peas, and in them we have plants showing a pair of marked and easily recognizable opposite characters. The tall and short forms are crossed with one another, and the seeds collected and sown. The resultant plants will be found to belong entirely to the tall variety, which has apparently wiped out the .short. If, however, this generation of seeds is sown and the flowers of the resultant plants be self-fertilized the result is that, when their seeds are sown, and have sprung up into plants, it is found that these are mixed, and mixed in definite proportions, for, on the average, it will be found that there are three (all forms for every one of the short. It follows that the dwarf- ishness was not wiped out, but that it was temporarily obscured in the second generation, though ]5reseiit all the time potentially. To the character which alone appears in the first cross is given the nani(^ ihimimml (in this instance tallness is dominant), and to the hidden character that of recesxive (dwarfi.shness, in the example). Wlien the tails and dwarfs of the