The Cortical Layer Theory " Nailed," and the fact that Peach and Wild Goose Plums do Hybridize Demonstrated.

In the Gardeners'Monthly for July 1887, p. 217, under the head of "Cortical Peculiarities in the Plum," there is evidently an intention to make an argument on the negative side of the " Peach and Plum Hybrid " question, based upon the one obscure subject of the Cortical Layer. However, there is more space in said article considering the flower and leaf peculiarities of some specimens of supposed peach and plum hybrids sent to the Academy of Natural Sciences of Philadelphia for examination, than to the consideration of their peculiar cortical layers, and the assertion, " It is due to science to say these specimens did not prove it," that is, that the peach and plum would hybridize, seems a little prejudiced, as the sequel will show.

From all the circumstances it is inferred that the specimens referred to were, at least in part, originally sent by the writer to the Editor of the Gardeners' Monthly, and noticed by him in the Monthly for May. Hence, as " it is due to science," to have the exact facts in this important matter, for they involve an important subject in scientific horticulture, it falls to me to arise and give the facts, if I can, and let the reader say whether the theory that peach and plum do, or do not hybridize, is true.

So, here goes for the facts. Let me remark at the start, that upon such facts rests the final conclusion, anyway, in case of all supposed hybrids, even though produced by the most skillful hybridizer, as we have seen in the case of several grapes turned out by some of our best hybridizers. A variety may have been produced by careful manipulation, and, a hybrid supposed certainly to have been produced between Labrusca and Vinifera, for example; yet when the plant develops and all through life and in its seedlings gives no evidence of any blood but Labrusca, we are forced to conclude there must have been a failure somewhere in the hybridizing act. I make this remark, to answer the opposite side in its demand for me to demonstrate by actually producing a hybrid. My answer to that is, that there is a ground of determination still behind that, and to which itself must yield. That is, the ground of botanical, or specific characteristics contained within the subject itself or in its progeny. I am glad the Academy of Natural Sciences of Philadelphia, has placed the solution of the problem upon the right basis here, so we shall proceed. But first I must note a fallacy of substitution offered the writer in good faith as a valid argument.

Not long since I sent the Editor of the Gardeners' Monthly, some eighteen or twenty leaves, picked from as many different trees, belonging to the two genera, Prunus and Amygdalus. No less than sixteen of the leaves were taken from the Wild Goose Plum and its certainly known seedlings, while two were pure peach. I simply asked the Editor to point out the leaves of this lot which belonged to these well-known genera, Prunus and Amygdalus. Now note his reply. Says he, " No botanist can tell a genus by the leaves, with any certainty. It is not possible to tell sometimes even the orders." Then he sent me a leaf of each from a Geranium and an Anemone, exceedingly resembling each other.

Such an argument of substitution would certainly nonplus one not accustomed to it. Occasionally in nature similarity is very striking, while relationship and identity are wide apart. There is a butterfly (Kallima paralekta) in Sumatra, which when in repose with wings closed, sitting upon the branch of certain plants cannot be distinguished from a leaf, only by the closest scrutiny.

To the common eye, the leaves of the Geranium and Anemone are almost exactly alike, but to the botanist, exceedingly different. With the leaf, the similarity ends; I did not send just two leaves, one each from different genera very similar. I sent a number of leaves (and could have sent as many more) from as many different known seedlings of the Wild Goose Plum, some of which closely resembled the parent, some the small leaved pine Chicasa Plum, and some so closely resembled peach, in size, shape, petiole, glands, margin, color, smell and taste, that he dare not attempt to say whether they were Prunus or Amygdalus. Not only do these leaves point in no other direction than to hybrid blood for their markings and properties, but the entire trees from which they came show combined peach and plum, while the female parent is as well known, as any such fact can be, to be the Wild Goose Plum. Below I give a careful analysis of different species of Prunus, of Amygdalus, and of these Wild goose Plum seedlings, some of which are supposed to be hybrids, with botanical characteristics carefully noted in presence of each tree, generalized from a great number of varieties. Draw your own conclusions.

Having seen thousands of Chicasa Plum seedlings grown from seed gathered where only this species grew near by, and all coming uniformly of the Chicasa type; and having seen several hundred of these Wild Goose seedlings grown from trees surrounded by peach and other plum trees blooming at the same time, and having for years watched them, am forced to the only (to me) tenable conclusion that they are hybrids. So far all are sterile, not because the pistils are monstrosities, but because they are hybrids of such nature that they cannot or do not hold, in most cases even the buds, but cast them without any perceivable cause, before they open, and that all would have monstrous organs when they would bloom is mere assumption. I still look for some of these yet to fruit. The Blackman has produced a few specimens here, large and fine; generally it fails.

No person can draw such correct conclusions of the true character of these forms as he who sees them in their entire aspect growing among plum and peach trees of every species and numerous varieties, as has been the fortunate lot of the writer. To see them and know them is to be convinced beyond the shadow of a doubt. We have entirely too many "monstrosities" (as friend Meehan puts it) coming together here to satisfy a good student of nature that that is the correct conclusion.

Having seen and examined a number of the peach and plum hybrids described by Prof. Munson, of Texas, in the last number of the Gardeners' Monthly, as well as the Blackman plum (so-called?), I thought it only due to the fruit growers of the country and to science to say they were hybrids, and that they were sterile. But I had no idea of being the innocent cause of the discussion which has followed. However, after seeing the trees and studying their peculiar forms, leaves and bark, I feel satisfied that they are not mere sports or monstrosities. I think a little more observation might even convert you, too» Mr. Editor.

[The Editor has never said that the Blackman plum is not a hybrid, nor that there are no hybrids between plums and peaches, as contended for by many intelligent persons; but he has said that he has seen no evidence satisfactory to his mind that specimens submitted to him are hybrids.-Ed. G. M].