FROM the twin-spored genus we pass to another, in which the spores are usually divided into three cells, and which, from this cause, has been named _Triphragmium_. Only one species has hitherto been found in this country, and _that_ not very commonly, on the leaves of the meadow-sweet, _Spiræa ulmaria_ (Plate III. fig. 47). Externally, it much resembles, in the size and character of the pustules, many of the above-named brands, but when seen under the microscope this similarity disappears. In general outline the spores are nearly globose, and externally papillose. In one species, found on the Continent, but not hitherto in Great Britain, the spores are covered with curious long-hooked spines, by means of which they adhere tenaciously to each other. In germination, the spores of _Triphragmium_ do not offer any noteworthy deviation from those of _Puccinia_,[5] and the chief interest of our indigenous species lies in the three-celled form of its spores (fig. 48), to which occasionally those of _Puccinia variabilis_ approximate, and may be regarded as the link which unites the two genera. Footnote 5: Mr. Currey has only seen the tips of the germinating threads swell, and become septate, each of the joints thus formed falling off and germinating without producing spherical sporidia; whilst Tulasne figures globular sporidia, as will be seen in our fig. 49, reduced from the figure by Tulasne.—(_Vide_ Currey, in “Quarterly Journal of Microscopical Science,” 1857, pp. 117, &c.)