By Prof. W. G. Farlow. Published by the Boston Society of Natural History.

We are interested in botany for various reasons, but the hoticulturist before any other class is interested in the progress of mycology, or that department of botany which deals with mildews or moulds, or perhaps as many will understand mere "blights." Unfortunately these little plants require microscopes of high power, as well as experience in their use, in order to investigate properly; and, in addition, a persevering study of the very highest character in order to understand what the microscope reveals. The average horticulturist has not the opportunity for this; and thus the very class above all interested are practically shut out from getting knowledge of their own on a subject of the most vital importance to that class. Those, however, who have been able to get a little insight into this curious study, find so much that is truly wonderful as to become enraptured with it, and do not wonder that those who know nothing speak of them in horticultural meetings as "fungi-mad," when they show how so many of the diseases of plants, hitherto supposed to be mysterious, are to be referred in the first place to the growth of these invisible organisms.

Indeed, those of us who have endeavored to follow in the track of this branch of science, are often astounded at what we are compelled to learn. When Oersted, the Danish botanist, told us that wheat rust and berberry rust were really forms of the same thing, we felt a little sore to think that we had been for so many years laughing at the "ignorant" farmer, because he had found by mere observation that the berberry always rusted when it grew near rusted wheat, and he was sure it must be the same thing. It is in this'direction we are still going, and Professor Farlow is here driving us along in the same road. Last year, when we called attention to the "yellow apple trees" of New Jersey, and said it must be from a species of Roestelia, Professor Buckhout explained in our pages that this fungus which so completely spotted the leaves with yellow, was only another form of the common cedar apple, well known for bursting out into yellow gelatinous threads after a shower of rain. Prof. Farlow here furnishes the evidence of this, but extends the knowledge so as to include an immense number of genera and species of parasite fungi. They are all mere forms of one and the same thing.

Into the few genera and species they really belong, is the task undertaken here to place.

Of course we are met here by the same old story, what is the use of all this minute study to the practical man. And we have still only the same answer, we do not know. No doubt the dull Spaniards asked of Columbus what good it did to wander along the sea coast and pick up the driftwood and "sea-beans" which the Gulf streams cast upon the Spanish shore. He did not know, and he could not help their laughing at his waste of such precious time. But we who are now enjoying the manifold blessings of the new world, know now what neither he nor they knew then, and say to all such students, prosper on. We may not now know just how such a mass of laboriously gained knowledge as is here given us by Prof. Farlow will benefit mankind any more than the old folks knew that Columbus' studies in driftwood would end in the discoveries of a continent;'but the benefit will all show itself in time, and the horticulturist especially will be among the first to get the benefit of Prof. Farlow's patient work.