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Popular Science Monthly/Volume 26/February 1885/Correspondence

< Popular Science Monthly‎ | Volume 26‎ | February 1885



Messrs. Editors;

IN reading the interesting article by Grant Allen on "Queer Flowers," in the December number of this "Monthly," I observe some statements concerning the fig which observation here in California, where the tree is very common and grows luxuriantly, does not confirm. In the first place, the caprifico does not, so far as I am aware, grow here at all. We realize, therefore, a condition the same as though it had "become extinct"; and yet the supply of figs—"best Eleme in layers"—has not "ceased entirely." On the contrary, figs here in the city are a drug, and are literally trodden under foot of men on the sidewalks over-hung by the trees; and in the country they lie rotting on the ground in thousands upon thousands for lack of the labor and care necessary for their marketing or preservation. This looks as though the "true figs" were not "dependent upon it (the caprifico) for pollen," as the writer states; and I am inclined to think that the "extraordinary and complicated cross-relationship" to which, according to Mr. Allen, the flowers of the fig owe their fertilization, is a myth, and, on the strength of the argument a posteriori alone, should be relegated to books for the nursery.

But, in addition to this, let us look at the (literally) internal evidence afforded by the fig itself against this mythical cross-relationship. The flowers of the fig, growing as stated on the inside of the hollow stalk or receptacle, which forms when ripe the main bulk of what is popularly known as a fig, are of two kinds, viz., male and female, that is to say, the male, or pollen-bearing organs (stamens), and the female, or seed-bearing organs (pistils), are borne on separate stalks, just as in the melon and cucumber. But while in the last-named plants the different flowers are placed at some distance apart on the vine, here they are crowded together in the hollow receptacle in close contact and in almost every conceivable relative position, above, below, and on all sides; and the hollow receptacle is all but completely closed by an irregular fringe of metamorphosed bracts which surround the eye ("hole," by courtesy) in the distal end. They (the flowers) are, therefore, in the best possible condition for self-fertilization, without any external aid from insects. The fig, in fact, presents in its synconium an analogy to the perfect Cleistogamous flowers found scattered through several orders and genera, which, although containing both stamens and pistils, do not open out or bloom, yet nevertheless, producing abundance of seeds, prove them-selves to be self-fertile.

Note here, however, that I do not assert that the flowers of the fig are generally or in any great number fertile; indeed, I have reasons to doubt this being so, for I have yet to see the first seedling fig-tree. And yet, from the great number of seeds (fruits?) falling on the ground and being covered up every season, it would seem almost certain that, if they were generally fertile, at least a few would germinate; and this brings me to another statement of our talented writer, which will bear examination before acceptance, viz.: " . . . as the figs won’t properly swell without fertilization, . . . and for this reason the Italian peasants hang on the tree small branches of the caprifico . . . at the moment when the eye of the fig opens, and so shows that they (the Flowers) are ready to be fertilized. The wasps . . . enter the figs at once and there set the little hard seeds, on whose fertilization the pulpy part of the fig begins to swell." The italics arc mine.

Is it certain that the swelling or ripening of the fig is at all dependent on the fertilization of its contained flowers or any of them? The pineapple presents a case in point which negatives the proposition, at least as a general one. Here the flowers are on the outside of a simple axis, in form of a spike. The axis continues growing beyond the spike of flowers, and may be cut off and rooted to form a new plant; in fact, this is the common and, I believe, the only mode of its propagation. Now, the pineapple as a fruit is formed by the axis, together with the surrounding and constituent flowers, bracts, etc., swelling and blending together in ripening into a fleshy, juicy mass, but the flowers are sterile and seedless. The plantain and banana likewise both ripen their fruits without the fertilization of their seeds. Although I am not in possession of conclusive evidence on this point, I am disposed to think, from some facts already stated, that the fig (through long continued propagation by layers or cuttings?) is approaching the condition of a seedless plant. Be this as it may, it has, I think, been shown that the "fig-wasp" may be stricken out of the account as surplusage, together with the pollen of the caprifico, with the result of no fewer figs and a nearer approach to the true story of the Ficus carica.

George Pyburn.
Sacramento, California, December, 1884

Messrs. Editors;

While several students of the University of Nebraska were geologizing in an outcrop of the Dakota group, situated in the western portion of Lancaster County, Nebraska, about thirteen miles west of Lincoln, they brought to light a curious freak of Nature. This was a leaf-impression, or rather the fragment of an impression, that preserved the green color which it wore several million years ago at the commencement of the Cretaceous period in geological time.

The deposit in which the leaf was found is a maroon-tinted sandstone, quite soft when first quarried, but solidifying rapidly after exposure to the atmosphere. The total thickness of the layers which outcrop at this point is about forty feet. The true dip is too slight to be accurately measured.

None of the layers of sandstone—and this is the sole kind of rock found in the Dakota group of Lancaster County—are of the peculiar reddish shade except that which contains the leaves. This layer averages nine inches in thickness, and is situated near the upper surface of the group.

The leaf-impressions obtained were many of them very beautiful and complete, representing various species of Juglans, Laurea, Liquidambar, Salix, and Quereus, with many others. They were very numerous, as many as two thousand specimens being obtained in a few hours.

The unique green leaf-fragment was too small to allow of successfully determining its genus or species. It is probably Laurea, however, since it was found in a mass containing impressions of Laurea almost exclusively.

C. G. McMillan.
1503 H Street, Lincoln, Nebraska,

October 23, 1884.