Popular Science Monthly/Volume 10/November 1876/Correspondence
To the Editor of the Popular Science Monthly.
DEAR SIR: It has always been a matter of surprise to me that some of my contributions to botanical science should be regarded as attacks on the doctrines of Darwin, or as opposed to theories of evolution. At the conclusion of the reading of my papers it is often a subject of argument on which side I stand. So great is this nervousness, that at Buffalo, because I showed that the ova-pollen of a yucca-flower was as potent as any that could be brought from another flower by an insect, I had to endure a sharp lecture from Prof. Riley, and even Prof. Morse could only help me with the audience by remarking, "We all know that Mr. Meehan is a Darwinian and an evolutionist, but must say that he has an odd way of putting it." That my good friend does not regard me as much of either is, however, clear, from his making no reference to any of my labors in his "History of Evolution."
For my own part I have not cared to be classed nominally with any party in science, but to let the facts I record speak for them-selves. My ambition has been to be considered a worker in the field of original observation and research, and, if I know myself, am indifferent whether the facts help my own or any other person's beliefs or theories. Still, even an observer must have some idea of the bearing of what he sees on evolution and Darwinism, if he think at all about these things. I have thought it would do no harm if for once I entered the speculative field and put my own interpretation on the facts as I have recorded them.
Instead of opposing evolution, I think my Hartford paper was a contribution to its cause. I not only showed that in plants there is an evolution of form by slow and gradual modifications through long series of years, but also that evolution is often by sudden leaps, and v that these sudden entrances were just as permanent, when the agents in natural selection favored, as any new form gradually evolved could be. I also showed the probability of whole districts changing by the operation of some inherent law, which would make the doctrine of evolution possible to those who can hardly believe every individual in a species came from one primordial form, one exact mathematical centre. Of course, so wide a generalization could not, ought not, to rest on so small a number of facts; but surely any one can see that if there be, and have been through all ages, change by sudden introductions as well as by slow modifications, there is no use in hunting in all cases for "missing links" that never existed; and I have found a plank on which Agassiz and his friends might have stood with Darwin; and I could render no better service to evolutionary views.
So in reference to cross-fertilization by insect agency, I regard myself as saving Darwinians from themselves. By cutting-out a rotten branch the tree is made healthier, and the possibility of a fall prevented to those who might crawl out on it. To my mind, there is nothing more opposed to the idea of natural selection than the modern doctrines in relation to insects and fertilization. Supposing that, in accordance with the inherent tendency to variation, a new form—a slight change—occurs that renders the plant better fitted to engage in the "struggle for life" than its parent, and that it is unable to make use of its own pollen, but must have pollen by insect agency from some other flower. The advantage it has gained is at once lost, as the crossed progeny of course is brought back to near its grandparent, and these again crossed with the foreign pollen are again reduced, till in the course of a few generations the variety is near enough to be the same. The effect of continual adding of water to milk is well known. In the supposed case of our plant, it becomes "watered stock" with a vengeance. If the new form could have the power of reproducing itself exactly, and thus continue to fix a habit, as we can understand it might do in using its own pollen, we can see how "natural selection" could use "variation" to advantage. The insect only interferes with the law.
There are some few plants which never seem to fertilize except by insect or other aid. In a large number of these cases their own pollen is just as good as foreign pollen. In a few instances foreign pollen alone seems to be potent. Why must we believe, in this latter case, that it is because their own pollen is designed to be inferior, in order that foreign pollen may be brought to it? There may be many other reasons. At any rate, the creed presented to us is inconsistent with a full idea of natural selection. The survival of the fittest will be most assured by an abundance of resources. The little chickweed which flowers and seeds with the thermometer at 35°, and the common erophila at 40°, are much "fitter" to fight their way through the world in the wonderful way they do than if they waited for the spring insect to bring them foreign pollen. We can readily understand that if a flower is diseased, the pollen of that flower acting on itself would produce diseased off-spring. Foreign pollen would bring back the health. With the millions of healthy flowers reproducing, the one flower diseased seems but trifling; but even so the insects can carry bad pollen to good flowers, as well as bring good pollen to diseased ones. Only that I have heard the argument from the highest in scientific standing, it would seem too puerile to mention here.
Without going further into detail, I may say that, as a matter of opinion, the observations I have placed on record aid evolutionary views in some of their weakest points, while I am really saving the doctrines of the survival of the fittest and of natural selection from injuries dealt out to them in the house of their friends.
|Germantown, Pa., September 28, 1876.|