It may seem surprising that a work of such importance should so long have failed to find recognition and to become current in the world of science. It is true that the Journal in which it appeared is scarce, but this circumstance has seldom long delayed general recognition. The cause is unquestionably to be found in that neglect of the experimental study of the problem of species which supervened on the general acceptance of the Darwinian doctrine. The problem of species, as Kölreuter, Gärtner, Naudin, Wichura, and the hybridists of the middle of the nineteenth century conceived it, attracted thenceforth no workers.
The question, it was imagined, had been answered and the debate ended. No one felt much interest in the matter. A host of other lines of work was suddenly opened up, and in 1865 the more original investigators naturally found these new methods of research more attractive than the tedious observations of hybridizers, whose inquiries were supposed, moreover, to have led to no definite results.
In 1868 appeared the first edition of Darwin's Animals and Plants, marking the very zenith of these studies with regard to hybrids and the questions in heredity which they illustrate, and thenceforth the decline in the experimental investigation of evolution and the problem of species have been studied. With the rediscovery and confirmation of Mendel's work by de Vries, Correns and Tschermak in 1900 a new era begins. Had Mendel's work come into the hands of Darwin it is not too much to say that the history of the development of evolutionary philosophy would have been very different from that which we have witnessed.
That Mendel's work, appearing as it did at a moment when several naturalists of the first rank were still occupied with these problems, should have passed wholly unnoted, will always remain inexplicable, the more so as the Brünn society exchanged its publication with most of the great academies of Europe, including both the Royal and the Linnean societies of London.
The whole history of Mendel's work, its long period without effect upon scientific thought, its thoroughly simple yet satisfactory character, its basis in manifold observations of problems simplified to the last degree, and its present complete acceptance illustrate very well the chief defect of the last two generations of workers in biology. [{221}] There has been entirely too much theorizing, too much effort at observations for the purpose of bolstering up preconceived ideas--preaccepted dogmas of science that have proved false in the end--and too little straightforward observation and simple reporting of the facts without trying to have them fit into any theory prematurely, that is until their true place was found. This will be the criterion by which the latter half of nineteenth century biology will be judged; and because of failure here much of our supposed progress will have no effect on the current of biological progress, but will represent only an eddy in which there was no end of bustling movement manifest but no real advance.
As stated very clearly by Professor Morgan at the beginning of this paper, and Professor Bateson near the end, Darwin's doctrine of natural selection as the main factor in evolution and its practically universal premature acceptance by scientific workers in biology are undoubtedly responsible for this. The present generation may well be warned, then, not to surrender their judgment to taking theories, but to wait in patience for the facts in the case, working, not theorizing, while they wait.