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قراءة كتاب Northern Nut Growers Association, Report of the Proceedings at the Third Annual Meeting Lancaster, Pennsylvania, December 18 and 19, 1912
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Northern Nut Growers Association, Report of the Proceedings at the Third Annual Meeting Lancaster, Pennsylvania, December 18 and 19, 1912
(Hicoria glabra) evidently pollinized on one side by the bitternut and on the other side by the shagbark These points are made for the purpose of showing the necessity of covering the female flowers with bags in our nut tree hybridizations. We must sprinkle Persian insect powder inside the bags or insects will increase under protection. When we have placed bags over female flowers, it is necessary to mark the limb; otherwise, other nuts borne on neighboring limbs will be mistaken for the hybridized nuts unless we carefully place a mark about the limb. Copper wire twisted loosely is, I find, the best. Copper wire carrying a copper tag with the names of the trees which are crossed is best. If I mark the limb with string or with strong cord I find there are many ways for its disappearance. Early in the spring the birds like it so well that they will untie square knots in order to put it into their nests. Later in the season the squirrels will bite off these marks made with cords for no other purpose, so far as I know, except satisfying a love of mischief. Now I am not psychologist enough to state that this is the reason for the action of the red squirrel, and can only remember that when I was a boy I used to do things that the red squirrel now does. (Laughter.) Consequently, on that basis, I traced the psychology back to plain pure mischief. Red squirrels and white footed mice must be looked after with great care in our hybridized trees. If the squirrels cannot get at a nut that is surrounded by wire cloth, they will cut off the branch and allow it to fall to the ground and then manage to get it out. White footed mice will make their way through wire, and mice and squirrels will both manage to bite through wire cloth unless it is very strong in order to get at the nut. The mere fact of nuts being protected by wire cloth or in other ways seems to attract the attention of squirrels. One of my men, a Russian, said, in rather broken English, "Me try remember which nuts pollinized; no put on wire, no put on tag, no put on nothing; squirrel see that, see right straight, bite off one where you put sign for him." (Laughter.) The best way for keeping squirrels and white footed mice from ascending a tree, I find is by tacking common tin, slippery smooth tin, around the trunk of the tree and this may be left on only during the time when squirrels are likely to ascend the tree. They will begin long before the nuts are ripe. In the case of hazel nuts, I have surrounded the bushes with a wire fence or wire mesh, leaving a little opening on one side, and have placed steel traps in the opening. Now here enters a danger which one does not learn about excepting from practical experience. I went out one morning shortly after having thought of this bright idea and found two gray squirrels in the traps. They had followed their natural instinct of climbing when they got into the steel traps, and climbing wildly had broken off every single branch from those hazels which carried hybridized nuts. There wasn't one left, because the squirrels when caught had climbed into the trees and had so violently torn about with trap and chain that they had broken off every single branch with a nut on it. So many things happen in our experiments that appeal to one's sense of the ludicrous, if he has a sense of humor, that I assure you nut raising is a source of great delight to those who are fond of the drama.
The field of hybridizing nut trees offers enormous prospects. We are only just upon the margin of this field, just beginning to look into the vista. It has been done only in a limited way, so far, by crossing pollen and flowers under quite normal conditions. We may look forward to extending the range now of pollinization from knowledge based upon the experiments of Loeb and his followers in biology. They have succeeded in developing embryos from the eggs of the sea urchin, of the nereis, and of mollusks, without spermatozoa. Their work has shown that each egg is a single cell with a cell membrane and it is only necessary to destroy this cell membrane according to a definite plan to start that egg to growing. Life may be started from the egg in certain species without the presence of the other sex. This may lead us into a tremendous new field in our horticultural work. We may be able to treat germ cells with acids or other substances which destroy the cell membrane so as to allow crossing between very widely separated species and genera. Loeb, by destroying the cell membrane of the sea urchin, was enabled to cross the sea urchin with the star fish, and no one knows but we may be able, following this line of experimentation, eventually to cross the shagbark hickory with a pumpkin and get a shagbark hickory nut half the size of the pumpkin. That is all! (Applause.)
(President Morris then took the chair.)
The Chairman: Please let me add that the hickory pumpkin idea is not to be taken seriously. That is a highly speculative proposition. I have found some times that, in a very scientific audience, men who were trained in methods of science, had very little selvage of humor,—little margin for any pleasantry, but this highly speculative suggestion, curiously enough, is not in fact more speculative than would have been the idea twelve years ago that you could hatch an egg, start an egg to development—without fertilization.
Mr. Hutt: I would like to ask how widely you have been able to cross species?
The Chairman: It has been possible to cross species of hazels freely with the four species that I have used, the American hazel, Corylus Americana; the beak hazel, Corylus rostrata; the Asiatic, Corylus colurna, and Corylus pontica. These apparently cross readily back and forth. With the hickories I think rather free hybridization occurs back and forth among all, but particularly in relation to groups. The open-bud hickories, comprising the pecan, the bitternut, the water hickory, and the nutmeg hickory, apparently, from my experiments, cross much more readily among each other than they cross with the scale-bud hickories. The scale-bud hickories appear to cross much more freely among each other than they cross with the open-bud hickories; not only species but genera may be crossed, and I find that the walnuts apparently cross freely with the open-bud hickories and the open-bud hickories cross with the walnuts. I have thirty-two crosses between the bitternut hickory and our common butternut, growing. All of the walnuts apparently cross rather freely back and forth with each other. I have not secured fertile nuts between the oaks and chestnuts, but I believe that we may get fertile nuts eventually. The nuts fill well upon these two trees fertilized with each others' pollen respectively, but I have not as yet secured fertile ones. We shall find some fertile crosses I think between oaks and chestnuts, when enough species have been tried.
Mr. Hutt: Do you notice any difference in the shapes of any of those hybrids, the nuts, when you get them matured and harvested? Do they look any different from the other nuts on the tree?
The Chairman: There isn't very much difference, but I seem to think that sometimes the pollen has exercised an influence upon the nuts of the year. Theoretically it should not do so, but I noticed one case apparently in which I crossed a chinkapin with a Chinese chestnut, and the nuts of that year seemed to me to present some of the Chinese chestnuts' characteristics.
Mr. Hutt: This year I crossed a number of varieties of pecans and in nearly all those crosses there was to me quite an evident difference in the nuts. For instance those gathered off certain parts of a pecan tree of certain varieties, Schley or Curtis or Frotscher, would be typical nuts, but those hybrids or crosses that I produced were distorted, more or less misshapen and seemed to have peculiarities; so that when we came to look over the colony we