Those who have been acquainted with the Dahlia for the last twenty-five years can not but be struck with the marvellous improvement it has undergone during that period. A little previous to that time they were what may be considered in the middle stage of their progress from the single and not very inviting "Wildings of Nature," to the highly improved condition now so strikingly manifested. To bring about this change, the labor of florists has been immense; and it is interesting to remember, what a degree of intelligence some of those in the vanguard exhibited in laying down a standard to which they would ultimately reach, at a time, too, when such flowers as we now possess were hut dimly foreshadowed by living forms, and had existence only in the dreams of enthusiasts; many of whom, as a matter of course, were sneered at by the "Jasper Standstills" of the day. Fastidious florists may have differed somewhat as to some of the particulars which they considered indispensable to the making up of a perfect flower; but there need be little difference now in regard to the leading points, as these are no longer subjects of speculation only, but are abundantly manifested in those varieties which occupy the post of honor in every good collection, and every exhibitor's stand.

It may seem of little importance what sort of footstalk a flower should have; whether long or short, stiff or slender; but, upon consideration, more depends upon this for showing a flower to advantage, than at first sight may appear. There are some good flowers with peduncles so short that they are hidden by the foliage, which greatly detracts from their bearing and show in the garden. It therefore seems a principle that the footstalks "be long enough, and not longer, than to carry the flowers clear of the foliage, and stiff enough to permit them only to lean a little to one side, as in this position they can be seen to greater advantage than when standing upright or nestling among the leaves. The new Dahlia, Emma Cheney, may be mentioned as affording a good illustration of what we mean, and which, by-the-way, is greatly at fault in this respect I had almost said the flowers of that variety are sessile; the footstalks are so short, however, as to necessitate the curious in many instances to turn aside the leaves before they can get a look of the flowers at all.

As to the flower itself, the point of greatest importance, and the one to which all the others are merely accessory, is that of form. Without this, color is but a poor recommendation, and size of small value. A flower may be all that can be desired in size, and adorned with the richest colors; but if the petals are coarse and ill shaped, and loosely or irregularly put together, its recommendations to notice would be perfectly unintelligible. On the other hand, if well formed, it can claim a place, although possessed of all other properties in a subordinate degree. "Two thirds of a ball when looked at sidewise" is the form most approved by those who have bestowed the greatest attention upon the subject Some of the best varieties, when well grown, come nearly up to this requirement The Duke of Roxburgh and Andrew Dodds are so near that little more can be desired. Take well-grown flowers of those varieties, and subject them to the most critical examination, the astonishment will be how they came to be so perfect. In size they are quite respectable, and in color the best in their classes.

If a flower of either is cut into two equal parts, one half laid flat upon a sheet of paper, and a line drawn around it with a pencil, touching the extreme points of the petals in the operation, the result will be a nearly perfect segment of a circle. 1 Were it entirely perfect, the highest point would be reached as regards form. When subjecting flowers to such an ordeal as this, their defects become very apparent, and their relative merits equally so. Some are too high on the shoulder, others too low; some too low in the centre, or hollow in the eye, as it is sometimes called; while others have petals so incapable of holding their form, that they get out of order, fall back, and go to decay before the centre petals are fully expanded. That is a perfect flower only, the first blown petals of which maintain their position to the last, or until those of the disc are fully developed. Carrie Emmons is one of those very defective as regards this point; therefore we think Carrie Emmons is not so good as has been represented, and by no means a first class Dahlia.

Then, again, looking at the individual petals of a first-rate flower, they are neither beaked, nor toothed, nor flat, nor reflexed, nor quilled, or funnel shaped, nor cupped, but smooth on the edges, and folded so as to be nearly elliptical in outline. And how admirably this form adapts them for constituting in the aggregate a perfect whole. Better than when quilled, as the spaces between the petals are less, and not so much of the under as the upper surface exposed, while a greater breadth of surface can be taken in at a glance. And better than when flat or reflexed, as the many waving lines, standing out in relief, are richer far than when they are flat or arranged in any other way. Another beautiful feature is the manner in which they are arranged. Beginning with the under petals, which invariably ought to be the largest, they "grow small by degrees,and beautifully less," until the summit is reached, where they should be so dense as to cover the entire disc, and not even a stamen or a scale be seen, and none the worse for leaning a little towards the center.

The imbrication should be perfect throughout, and each row of petals of a uniform length.

Of color I do not speak, as it is rather a perplexing subject, and seems to become more and more embarrassing by the giving of new terms - such as Mauve, and Solferino, and Magenta - to colors which, to my poor apprehension, are as old as the ass and the death of Abel. Be that as it may, however, we all derive much pure pleasure from looking upon flowers whose colors are clear, and bright, and dense, no matter of what shade they may be. The Dahlia is no exception in this respect, and the flowers with the richest colors, if otherwise good, will be the most sought after. Among the fancy varieties there are some very striking and fanciful shades. Those are the most beautiful which have a clear ground color, and when the markings contrast well with it, either by lacing the petals, or when laid on in flakes, or in distinct dots.