A leading pomologist, himself of great experience in crossing and hybridizing, writes : "When it can be shown that a long variety of a cucumber can, by immediate crossing, be made to produce a short one, or a crook-necked squash be transformed into one of turban form, then I shall have more confidence in the new theory. "

[Our correspondent makes a good point. So far as squashes, pumpkins and melons are concerned, there is not the slightest evidence that they have been immediately changed by the pollen of another variety. The "theory" is not exactly new. Some gentleman communicated to the Royal Horticultural Society of London, in the early part of the century, a paper, showing that a netted melon had produced smooth fruit as well on the same plant. This was assumed without the shadow of proof, to be from immediate action of pollen, - but we now know that changes in netting, like the russet of apples, can and do often come where there is certainly no chance for pollen influence. But from this paper appears to have arisen the "theory" that melons are immediately influenced. Livingstone's experience with bitter and sweet melons is another illustration. We know in these days how this saccharine principle is affected. A Rhode Island Greening, sour in the East, is sweet in California. Melons lose their flavor or change their form - degenerate is the word - just as often when wholly alone, as when they are near pumpkins or cucumbers.

On the other hand, the Hon. Simon Brown, of Concord, Mass., than whom New England produced no more intelligent or careful agriculturist, in a paper in the Reports of the Department of Agriculture - for 1863, if our memory serves us truly - states that careful experiments in growing all sorts of cucurbitaceous plants together, for the purpose of testing this very question, failed to show the slightest indication of change in any one of them.

We have looked carefully into the literature of the subject, and find no fact adduced in favor of this theory that cannot be better explained in the light of modern facts, except, possibly, Indian corn. - Ed. G. M].

At a recent meeting of the Academy of Natural Sciences, Mr. Thomas Meehan directed attention to an ear of Indian corn on the table, sent by Mr. Burnett Landreth, which had nearly all one side with brownish-red grain, the other side creamy white, which was the normal color of the variety. Usually the intermixture of colors which occasionally occurred in an ear of corn, is attributed to cross-fertilization. It is apparent that this could not be the case in this instance. The whole solid block is colored, and, at the edge of the colored mass, only half a grain would be colored in some instances. The coloring influence had evidently spread from some central point quite independent of any single grain, and had spread from grain to grain through the receptacle, until the coloring material was exhausted. In cross-fertilization, from the entangled position of the silk-like pistils no such regularity of coloring in adjoining grains could occur. On reflection we may understand that at times color in corn must come from causes independent of cross-fertilization, as the departure in the first instance from one color, must be from an innate power to vary in color, independently of any pollenating influence.

The facts are interesting, as bearing on many topics as yet not wholly solved. Much has been said about the changes in nature being by slow modifications through long ages, but we have frequent instances of sudden leaps. There are no gradations between the colors of these grains. Again, it is in dispute how far cross-fertilization influences the seed. Generally no immediate influence is conceded, we have to wait till the seed grows, and we can examine the new plant to ascertain the potency of the several parents. So far corn has been the chief and almost the only evidence that the seed or its surroundings are immediately affected; but recently statements have been made that the receptacle in the strawberry - what we know in every-day life as the strawberry - is similarly influenced. There are some varieties wholly pistillate, and it is claimed that when pollen is applied from other varieties, the resultant fruit is that of the male parent. It is of great practical importance that such a question should be decided by undoubted facts. Experience in other directions does not confirm these views. The Mitchella repens is really a dioecious plant.

Many years ago he found one plant with white berries, and removed some portion to his own grounds, where, isolated from others, it produces no fruit. In its native location it bears white berries freely, though the pollen is from the original scarlet berried forms. Mr. Jackson Dawson had given him a similar case on Prof.Sargent's grounds, where a white berried Prinos verticillatus is produced, though it must have pollen from the original red berried form. Other illustrations were referred to.

To those who looked for regularity of rule in these cases, and in the light of the specimen of corn before the meeting, there might be a doubt whether the variation in corn often attributed to cross-fertilization, may not after all have resulted from an innate power to vary. It did not really follow that the rule should be uniform, for those who had experience in hybridizing knew how variable were the results, even from the seed of a single flower. Parkman had obtained in lilies seedlings so exactly like the female parent, that only for the remarkable form from the same seed vessel known as Lilium Parkmani, it might have been doubted if some mistake as to the use of foreign pollen had not been made. If so little influence could occasionally be found at a remote end of the line, we may reasonably look for an immediate influence at the nearer end in some exceptional cases. But there appeared to be no carefully conducted experiments on corn recorded anywhere, though the belief in the immediate influence of strange pollen is a reasonable one, so far as general observation goes.

It seemed, however, to him, with the specimen of innate variation in corn before us, more careful experiments with corn and other things are desirable.

A correspondent says : "In the March number of the Monthly you seem to regard it as an impossibility that, in any case of hybridization, the strange pollen should produce a modification of the ovary. That it does not, at least to a perceptible degree, in a majority of cases, must be true, else it could not have escaped the notice of watchful eyes. But it is hardly safe to lay down a uniform rule, and say that it never does, and never can. All pollens do not act alike. No doubt, the ovaries of myriads of plants have their stigmas visited by the pollen-cells of other species, flowering at the same time, and those often nearly allied, as for instance in the genus Quercus, and yet their ovules are not affected. Here and there they are, and hybrids result. Why may not the modifying influence extend further, though more rarely, to the ovary itself? The puncture of the ovipositors of most insects leaves only a scar on the stalk or leaf, but in some cases, the vegetable forces are so diverted that growths of singular shapes are produced for the accommodation of the ova, each of its own kind. After all, theory must give way to fact, and one good example is enough.

Whilst living in Lancaster, Pa., I planted seeds of the nutmeg variety of the canteloupe, in hills, in a bed at the end of my garden, and, on one side of this bed a few hills of cucumbers. As the canteloupes developed, those lying next the cucumbers assumed a decidedly oblong shape,and were smooth on the surface; of a deep green color, and when cut, watery and possessed of a cucumber-like odor and taste. Those on the other border, removed from the cucumbers, were of the normal shape, round, grooved, rough, of a grayish hue, and ripened into fruit possessed of all the qualities of that delicious variety of the canteloupe. Was I wrong in attributing the ruin of half my bed of melons to the agency of cucumber pollen? As you have means to do it, test my statement by experimenting the same way next summer, and report the result".

[It was far from the Editor's intention to suggest the impossibility of this immediate influence, but to show that evidence readily within the reach of any person, namely, direct experiment, has never proved the point. Direct evidence has been attempted, and recorded years ago in the transactions of the Royal Horticultural Society, but that evidence went the other way ! Now what a good chance was lost by our correspondent. With such excellent grounds for suspicion, if he had planted a melon wholly by itself the next year, cut off the male blossoms before opening, and given it nothing but cucumber pollen, he could have now told us all about it. - Ed. G. M.].

At the meeting of the American Pomological Society Prof. Lazenby said that his experiments with the Crescent strawberry, though showing some immediate influence he thought, were not as satisfactory as those of the previous year.

Mr. Fuller took a more advanced view than any yet recorded; the pollen had not only an immediate influence on the fruit, but also on the whole plant. A detail of the facts on which Mr. Fuller bases this conclusion will be looked for with much interest.