The December American Naturalist has a paper by Prof. J. C. Arthur, which is one of the most satisfactory we have read for a long time, and is well worthy of perusal by those interested in intelligent pomology. It is long since the Gardeners' Monthly took the stand that fire blight must of necessity be of fungus origin, because it was not possible to introduce any supposition on the other grounds of climate, soil, modes of culture, etc, without the proposition carrying with it its own refutation. It was evident that the cause, whatever it might be, was local, and therefore induced by some special influence operating on particular parts of a tree, wholly independent of the plant itself. In other words, some parasitic action must be the acting power in inducing fire blight. Though predisposed this way, we have not hesitated to criticise theories offered in its defence, because we think nothing should be accepted as science, that will not bear every attack. Professor Burrill's proposition that the disease was caused by the presence of Bacteria, was fully in accord with our prepossessions; still we have not hesitated to point out occasionally, weak points; and quite recently, in noticing another paper by Prof. Arthur, we had occasion to observe that there was still left a doubt, whether what was generally known as fire blight, was the disease Prof. Arthur had in his mind.

In this paper he has made it clear, that it is the genuine fire blight with which he has been experimenting, though it is also clear that some diseases, or perhaps forms of the real disease, but not the genuine article, are sometimes confused. There is still one point which the Professor does not seem to have observed, and which we think very important to a correct diagnosis of the case, and that is, that the part attacked is really but a very small portion of the branch - an inch or two in most cases - and the rest of the branch is, as he states, killed simply through the destruction in the ascent of the sap. Usually the ringing of a branch, by which the sap would be obstructed, would not result in an immediate blackening of the leaves; they would gradually wither, and finally die away brown instead of black; and this reflection would indicate that there is yet something more than a mere cutting off of the sap supply. Still, the candid reader will have to admit, that the results of Professor Arthur leave but little doubt that a species of Micrococcus, allied to Bacteria, is at the bottom of all the trouble.

It is only its " ways and means " that are yet to be found out.