Although not exactly fruit, it is, no doubt, the means by which the Vorticellæ are propagated, for it is known that many fixed zoophytes, and even some plants, produce free swimming germs or spores, which afterwards become fixed, and grow up into forms like those which produced them. In some of the branching zoophytes (_Coryne_, _Sertularia_, &c.), the germs are exactly like little medusae, being small, gelatinous cups fringed with tentacula, by means of which they twitch themselves along with surprising agility. In this Vorticella, however, it is more like one of the ciliated Infusoria. The first one that I saw attached I conceived to be a remarkably large bell, with its mouth directed towards me, but the cilia with which it appeared to be fringed were unusually large and distinct. The movements of these appendages being comparatively slow, it was most interesting to watch them as they successively bent inwards and rose again, like the steady swell of a tidal wave, or an eccentric movement in some piece of machinery, making a revolution about twice in a second, and in the opposite direction to the hands of a clock. Suddenly the tree contracted, when, to my surprise, I observed the bell, which not an instant before appeared attached, now floating freely in the water, its ciliary movements not being in the least interrupted. Presently, however, they became brisker, the bell turned over on its side, and, ere the tree had again expanded, darted out of view, not, however, before I had remarked that it was not a bell, but a sphere flattened on one side, and having its circular ring of cilia on the flat side, with only a slight depression in the middle of it. There also appeared to be a small granular nucleus immediately above this depression, the rest of the body being perfectly transparent. I afterwards saw several others attached to the tree, each seated about the centre of a branch; but none of these were so fully developed. They were like little transparent button mushrooms, and had all more or less of a nucleus on the side by which they were attached. On only one of these did I detect any cilia. Mr. Gosse, in his 'Tenby,' gives a picture of an animal exceedingly like what I have described; but from his account of it, there seems to be some doubt of their identity. He calls it '_Zoothamnium spirale_,' because the insertions of the branches were placed spirally around the main stem, like those of a fir-tree. In my specimens the branches were set alternately on opposite sides of the main trunk, and the whole was curved like a drooping fern leaf or an ostrich feather, the bells being mostly set on the convex side.