INFUSORIAL ANIMALCULES. 15 



CHAPTER I. 



INFUSORIAL ANIMALCULES. 



" Full Nature swarms with life ; one wondrous mass 

 Of animals, or atoms organized, 

 Waiting the vital breath when Parent-Heaven 

 Shall bid His spirit blow. The hoary fen, 

 In putrid streams, emits the living cloud 

 Of pestilence. Through subterranean cells, 

 Where searching sunbeams scarce can find a way, 

 Earth animated heaves and where the pool 

 Stands mantled o'er with green, invisible, 

 Amid the floating verdure millions stray. 

 Each liquid too, whether it pierces, soothes, 

 Inflames, refreshes or exalts the taste, 

 With various forms abounds. Nor is the stream 

 Of purest crystal, nor the lucid air, 

 Though one transparent vacancy it seems, 

 Void of their unseen people." Thomson. 



THE name of infusorial animalcules has been given to various species of 

 minute living beings, which were first discovered in vegetable infusions ; that is, in 

 water containing vegetable matter. From the latter circumstance they received 

 the appellation infusorial, and in consequence of their being exceedingly small 

 they were termed animalcules or little animals. 



It was supposed by the earlier naturalists, that the animalcules, whose exist- 

 ence was thus detected, were confined to certain infusions ; but it is now well 

 ascertained that there is no necessary connexion between them and the vegetable 

 ingredients, except to this extent ; that the latter, under favorable circumstances, 

 may perhaps facilitate the development of the eggs of these living atoms, and 

 afford a proper nourishment for the animalcule, through all the stages of its 

 existence. 



As this department of nature became more thoroughly and widely explored, 

 new species of animalcules were discovered, and the general term of infusorial 

 animalcules, has therefore been so enlarged in its signification as to embrace, not 

 only that class of minute beings that are found in vegetable infusions, but all 

 those that possess the same marked peculiarities of structure, wherever discovered. 

 In the gushing fount, the rippling brook, and the placid waters of the lake, infu- 



