Mendel's principles of heredity: A defence

by William Bateson; Gregor Mendel

The next step was at once to defend Mendel from Professor Weldon. That could only be done by following this critic from statement to statement in detail, pointing out exactly where he has gone wrong, what he has misunderstood, what omitted, what introduced in error. With such matters it is easy to deal, and they would be as nothing could we find in his treatment some word of allusion to the future; some hint to the ignorant that this is a very big thing; some suggestion of what it all may mean if it be true.

Both to expose each error and to supply effectively what is wanting, within the limits of a brief article, written with the running pen, is difficult. For simplicity I have kept almost clear of reference to facts not directly connected with the text, and have foregone recital of the now long list of cases, both of plants and animals, where the Mendelian principles have already been perceived. These subjects are dealt with in a joint Report to the Evolution Committee of the Royal Society, made by Miss E. R. Saunders and myself, now in the Press. To Miss Saunders who has been associated with me in this work for several years I wish to express my great indebtedness. Much of the present article has indeed been written in consultation with her. The reader who seeks fuller statement of facts and conceptions is referred to the writings of other naturalists who have studied the phenomena at first hand (of which a bibliography is appended) and to our own Report.

I take this opportunity of acknowledging the unique facilities generously granted me, as representative of the Evolution Committee, by Messrs Sutton and Sons of Reading, to watch some of the many experiments they have in progress, to inspect their admirable records, and to utilise these facts for the advancement of the science of heredity. My studies at Reading have been for the most part confined to plants other than those immediately the subject of this discussion, but some time ago I availed myself of a kind permission to examine their stock of peas, thus obtaining information which, with other facts since supplied, has greatly assisted me in treating this subject.

I venture to express the conviction, that if the facts now before us are carefully studied, it will become evident that the experimental study of heredity, pursued on the lines Mendel has made possible, is second to no branch of science in the certainty and magnitude of the results it offers. This study has one advantage which no other line of scientific inquiry possesses, in that the special training necessary for such work is easily learnt in the practice of it, and can be learnt in no other way. All that is needed is the faithful resolve to scamp nothing.

If a tenth part of the labour and cost now devoted by leisured persons, in this country alone, to the collection and maintenance of species of animals and plants which have been collected a hundred times before, were applied to statistical experiments in heredity, the result in a few years would make a revolution not only in the industrial art of the breeder but in our views of heredity, species and variation. We have at last a brilliant method, and a solid basis from which to attack these problems, offering an opportunity to the pioneer such as occurs but seldom even in the history of modern science.

We have been told of late, more than once, that Biology must become an exact science. The same is my own fervent hope. But exactness is not always attainable by numerical precision: there have been students of Nature, untrained in statistical nicety, whose instinct for truth yet saved them from perverse inference, from slovenly argument, and from misuse of authorities, reiterated and grotesque.

The study of variation and heredity, in our ignorance of the causation of those phenomena, must be built of statistical data, as Mendel knew long ago; but, as he also perceived, the ground must be prepared by specific experiment. The phenomena of heredity and variation are specific, and give loose and deceptive answers to any but specific questions. That is where our exact science will begin. Otherwise we may one day see those huge foundations of “biometry” in ruins.

But Professor Weldon, by coincidence a vehement preacher of precision, in his haste to annul this first positive achievement of the precise method, dispenses for the moment even with those unpretending forms of precision which conventional naturalists have usefully practised. His essay is a strange symptom of our present state. The facts of variation and heredity are known to so few that anything passes for evidence; and if only a statement, or especially a conclusion, be negative, neither surprise nor suspicion are aroused. An author dealing in this fashion with subjects commonly studied, of which the literature is familiar and frequently verified, would meet with scant respect. The reader who has the patience to examine Professor Weldon’s array of objections will find that almost all are dispelled by no more elaborate process than a reference to the original records.

With sorrow I find such an article sent out to the world by a Journal bearing, in any association, the revered name of Francis Galton, or under the high sponsorship of Karl Pearson. I yield to no one in admiration of the genius of these men. Never can we sufficiently regret that those great intellects were not trained in the profession of the naturalist.

Mr Galton suggested that the new scientific firm should have a mathematician and a biologist as partners, and—soundest advice—a logician retained as consultant[2]. Biologist surely must one partner be, but it will never do to have him sleeping. In many well-regulated occupations there are persons known as “knockers-up,” whose thankless task it is to rouse others from their slumber, and tell them work-time is come round again. That part I am venturing to play this morning, and if I have knocked a trifle loud, it is because there is need.