Many have all the appearance of a precocious individuality. They do not long remain subject to the communistic life led by their immediate superiors, the true Polypes. Very many of these invisibles are individuals at the first leap; that is to say, that, at the first moment of their existence, they can come and go alone and at their own will; true citizens of the world whose movements depend only upon themselves. Whatever can be seen or imagined of various modes of locomotion in the visible world, is equalled, even surpassed, among these invisibles. The impetuous whirl of a potent star, of a sun which attracts around him, as his planets, the weaker one which he meets, the more irregular course of the eccentric comet, the graceful undulation of the slender one in the water or upon the land, the rocking barque that veers right round in an instant, the rush of the swift shark and the slow crawl of the wretched sloth--all and every movement, clumsy or graceful, slow or swift, is to be found in the various species of atoms. And with what a marvellous simplicity of machinery! Here you see one, a mere thread, advancing, twisting, a veritable elastic cork-screw; there you see one that for oar and rudder has only an undulating tail or a pair of little vibrating eye-lashes. The beautiful little polypus-worms, like flowers in a vase, anchor together upon an isle--a little plant, or a miniature crab, and then separate and cast off by detaching their delicate peduncle. What is even more surprising than the organs of motion, is what we may term the expression, the attitudes, the original signs of character and temper. You may recognize here the apathetic, there the vivacious and fantastic, some all alert for war, and others, as it would seem, fretful and agitated without any apparent cause. Again, you will occasionally see a whole crowd of remarkably quiet and peaceable atoms suddenly dispersed and knocked over by some scapegrace atom, conscious of superior strength, and spoiling for a fight. A prodigious comedy is that of our atoms! They seem to be satirically rehearsing the various farces which are played in our own noble and serious world, of atoms of larger growth! At the head of the infusoriæ, we must make respectful mention of the majestic giants, the highest type of motion and of strength, slow, but terrible and great.