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Page:Popular Science Monthly Volume 72.djvu/176

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POPULAR SCIENCE MONTHLY

However, putting aside the extraordinary scientific interest of such discoveries, and their bearing, ultimately, on the whole fabric of human thoughts; you will see readily enough that if a rust fungus can be transferred to a previously immune host through an intermediate form the planting of such a form in a certain region might be the cause of the ruin of a whole crop of wheat, oats, barley, or what not. Agriculturists have long sought, and thanks more especially to the knowledge derived from Mendel's researches, are learning how to isolate rust-proof types of cereals. In this way the pest may be overcome, but the vantage gained may again be lost in ways which would never be suspected, and could not be prevented, but for Dr. Arthur's illuminating researches.

Mr. W. L. Tower, of the University of Chicago, has been for many years conducting breeding experiments among beetles, choosing for that purpose the Colorado potato beetle and its immediate allies. Only the first part of his results has been published, but it is enough to show that he has found out some exceedingly interesting and important things and thrown new light on other matters not entirely new. For example, in breeding the beetles, he found that through a number of generations, the selection of extreme individuals (say dark, or light) for breeding did not sensibly modify the race. But by a process of very elaborate and careful breeding from isolated beetles, he discovered that sometimes a character was inherited fully, sometimes not to any appreciable degree, that is to say, it was possible to have two parents, AA and AB, looking exactly alike, but the first having, the second lacking, the property of producing offspring all closely similar to itself. The importance of such facts from an economic standpoint are hardly to be overestimated. Through such researches as those of Tower and Mendel, we are coming to understand why it is so difficult to improve a race by merely choosing those individuals which superficially appear to be of a desirable kind. It is necessary to isolate them, and test their properties through the character of their offspring, in order to separate pure races.

I have chosen only a few striking cases, and have said nothing about the infant ideas of our own vicinity. At some future time it may seem worth while to get up a local baby-show; the more so because, I regret to say, many of the infants known to me are lacking nurses, and I do not know of any hospitable door steps on which to leave them.

Ideas are not merely born once, but they suffer new births in the minds of many persons. In truth, they are not precisely repeated, but in each reincarnation are a little modified or augmented, so that the thought of every person about a given subject has its own individuality. This, however, presupposes that the child is alive, and not still-born. If it has any vitality, it will call attention to that fact by metaphorical