Unless some similar plan to the following be adopted for examining the species of this genus, it may result in disappointment; for the slight attachment of the joints to each other will otherwise present only a mass of simple echinulate cellules, if a portion be only removed from the leaf on the point of a lancet. This method consists in making a thin vertical section of a pustule in which the spores are contained; by this means the arrangement of the fruit and the mucedinous threads from whence they proceed may be observed. Any person possessed of the cardinal virtues of microscopy—patience and perseverance—will be rewarded in this instance; whilst those who are deficient will lose an object worthy of the virtues they dare not boast. But few instances have occurred in this and the preceding chapters in which the exercise of any great ingenuity or application has been called for; the most juvenile or truest tyro at the microscope may see for himself much of what has been indicated, whilst a few opportunities have occurred for more practised manipulists to prove that they are neither juveniles nor tyros. ------------------------------------------------------------------------ CHAPTER X. _WHITE RUSTS._ ALLUSION has already been made to the important memoir recently published by Dr. de Bary. “White rusts” occupy a conspicuous position in that memoir, and the experiments therein detailed, with the conclusions arrived at, will be largely drawn upon in furnishing the present chapter. Whilst believing that we have fairly represented the views, and faithfully narrated the story of research, if not literally, but denuded of some technicality, yet in such manner as to convey the sense of our author, we claim no originality or merit save for the garb in which it appears, without addition, stricture, or confirmation of our own.