We will walk to-day along the side of the canal bank as far as the aqueduct, then take the Duke's Drive and home by Lubstree Park; we shall find lots to see and to admire in the course of our ramble. We notice plenty of those beautiful balls of green jelly (_Ophrydium versatile_) in the clear water of the canal which, you know, we see every spring. These balls vary in size from that of a pea to that of Jack's fist; they are, you see, generally attached to some water-weed, and consist of myriads of very minute creatures called _infusoria_, which are imbedded in a mass of whitish jelly; these animals can detach themselves from the jelly and swim freely about; of course it requires a microscope to see the tiny green animalcules. If we examine a single specimen under a high power of the microscope we shall see its shape, which, when fully extended, is long and cylindrical, having at one end a mouth surrounded, as is usually the case in the _infusoria_, by a circle of very fine hairs, or _cilia_, as they are called, from the Latin word _cilium_ an eyelash; the mouth opens into a long narrow channel; the creature's throat, which leads to its stomach; towards the opposite extremity the animal tapers, till it ends in an extremely long fine hair-like tail which is fixed in the jelly-like ball; when the little creature prefers to swim freely about in the water it leaves its tail behind it, unlike, in this respect, to little Bo-peep's sheep! These balls were once supposed to belong to the vegetable kingdom, but there is no doubt about their animal nature.