232 THE MICROSCOPE AND ITS LESSONS. 



may see it ; but for the purpose of propagation, when the 

 proper period arrives, at the lower end of the body, at the 

 point of its junction with the stalk, a new fringe of cilia 

 is developed; and when this is fully formed, the vorti- 

 cella quits its stalk and casts itself freely upon its world 

 of waters. 



Pond-life! "I am free to confess," writes Mr. Gosse, 

 " that among all classes of animated beings the Rot if era 

 has been my own special delight. Their numerous and 

 varied forms, often of remarkable symmetry and elegance, 

 their swiftly revolving wheels, their vigorous and sprightly 

 motions, their curious habits and instincts, their complex 

 organization, and the ease and correctness with which 

 this is discerned through their tissues, which have the 

 transparent brilliance of the purest crystal all combine 

 to impart a charm to the wheel-bearers, which make the 

 observer hail their appearance in his drop of water with 

 pleasure, and linger over them with unwearied delight." 



Their little lives are indeed like a romance. You may 

 observe all its processes by dropping a little colouring 

 matter into the water in which you have found them, and 

 as the minute particles, either of indigo or carmine, pass 

 along their little canals, their envelopes being perfectly 

 transparent, the whole of the machinery of their exqui- 

 sitely perfect little bodies may be easily observed. 



Should it be asked what is the use of these apparently 

 useless little things these to us invisible inhabitants of 

 the watery world Professor Owen tells us that they are 

 the " invisible scavengers " who are appointed to preserve, 

 not only the purity of the water, but the salubrity of the 

 atmosphere, for they are found everywhere. Heated water 

 will not destroy them, for they know how to preserve an 

 atmosphere around their curious bodies just cool enough to 

 preserve life ; nor will frozen water exterminate them, for 



