174 THE HARMONIES OF NATURE. 



as, for instance, in the little pools left after rain, in the hollows 

 of the lead with which the tops of houses are partly covered, or 

 in cisterns which are not beneath roofs, or otherwise covered 

 over. Some species flourish attached to damp moss; others inhabit 

 the snows of the Alps, or the leaf-cells of Sphagnum, or the in- 

 testinal tube of the earthworm, or even the interior of the like- 

 wise microscopical Vol vox globator, devouring the colonies that 

 form within the cavity of its tiny globe, and replacing them, 

 cuckoo-like, with their own eggs. Several hundred species of 

 these interesting little animals have already been discovered, and 

 there can be no doubt of the existence of a vast number of still 

 unknown forms. 



Their tenacity of life is most remarkable, for they can be kept 

 in a state of complete dryness for any length of time, and will 

 yet revive very speedily upon being moistened. This fact, taken 

 in connection with that extraordinary rate of increase which 

 characterises all microscopical animals and plants (according to 

 the estimate of Professor Ehrenberg, nearly 17,000,000 may be 

 produced within twenty-four days from a single rotifer), removes 

 all difficulty in accounting for the extent of their diffusion, and 

 for their occurrence in incalculable numbers in situations where 

 a few days previously none were known to exist: for their entire 

 bodies may be wafted in a dry state, by the atmosphere, from 

 place to place, and their return to a state of active life, after 

 a desiccation of unlimited duration, may take place when- 

 ever they meet with the requisite conditions moisture, warmth, 

 and food. Thus the . insignificant Eotifera, the marvels of 

 whose organisation it requires the microscope to reveal, fully 

 exemplify the truth of the fine remark of Pliny, that Nature is 

 nowhere more admirable than in her smallest productions ! 



