say: "I am sorry it did not turn out thus and so; it would have been so fine if it only had been so." Let him be glad at discovering the truth. When he is eager for controversy, teach him the difference between discussion and controversy, and keep him out of the latter. Point out to him that erroneous conclusions are to be set aside, not so much by disproving them as by demonstrating the true conclusion. (Darwin's theory of pangenesis has been set aside, not by being disproved, but by the demonstration that the theory of germinal continuity is well founded. The cataclysmic theories of Adam Sedgwick and the older geologists have been overthrown by the accumulated proofs of the gradual character of geologic changes. An error is hard to kill, but with a truth you may drive it away; therefore research is better than controversy.
The love of one's own opinion is the most insidious and fruitful of all sources of human error, and accordingly we recognize vanity and self-conceit as the gravest of defects in the naturalist's character. It is easier to make a competent investigator out of a dull man than out of a conceited man.
A second source of error is impatience—impatience to get results before the data are sufficient to support conclusions. What a horrible record against this century has been piled up by the accumulation of "preliminary notices," "vorläufige Mittheilungen, and notes preventives!"—a vast mass of mistakes, a terrible impediment to science, and all to gratify the mad longing for priority. I wish that the publication of a preliminary notice to secure priority should disqualify for membership in this society, and I trust that every one of us will stand firmly and sternly against this abuse, which is doing more to degrade science than any other influence I know of. Indeed, I am almost ready to say that the Académie des Sciences at Paris has done more against science than for science, because in its Comptes-Rendus it initiated the custom of brief premature publication for priority.
A third difficulty in the way of reason is the tendency to speculate. The annual waste of cerebral protoplasm in speculation must amount to millions of pounds. A vast generalization has its allurements, but in yielding to them we are apt to be drawn away from the actual facts. There is another danger, for the mere lapse of time gives hypotheses a dignity and apparent worth, and it were easy to give illustrations. You are doubtless all familiar with the hypothesis of panmixia, which was advanced on the flimsiest of bases; yet a few years later its propounder treats it as an established law. The like misfortune might happen to any of us, since it is easy to remember the conclusion and to forget the evidence. Among zoölogists speculation has long been rife, and for many years we have been deluged with phylo-
