10 GENERAL HISTORY OP 



be coated with a thick green matter, abound with the 

 different species of the Euastra and Closterium, the Ar- 

 throdesmus quadricaudatus and pectinatus, the Stentor 

 polymorphus, and Vorticella chlorostigma ; and those 

 objects which have a bright orange-coloured coating, 

 derive it from the presence of the Stentor aureus. 



The abode of animalcules is not, however, confined to 

 the clear fresh water of lakes, rivers, pools, springs, and 

 trenches, but extends even to the briny ocean, to strong 

 acids, tannin, and the fluids contained in the animal and 

 vegetable creation. In moist earth, the species of Bacillaria 

 and other shelled animalcules may also be found; and 

 even the very air we breathe may teem with them and 

 their germs, whilst the gentlest breeze will be sufficient to 

 waft them in myriads over the distant waters, and to 

 transport these living atoms throughout the face of 

 Nature. So that, in short, whether we descend into the 

 deepest mines, where darkness ever reigns, or climb the 

 loftiest mountains, whose summits glow with almost per- 

 petual sunshine, there shall we find them located alike. 



Although the colouring of water is sometimes derived 

 from the oxides of iron and other mineral or earthy sub- 

 stances over which it flows, or from the Oscillatoria and 

 other minute algae which it contains, an intensity of 

 colouring will also be given it by the presence of infusorial 

 animalcules. Thus the Astasia imparts a blood-red 

 colour, as also the Euglena ruber; the Gallionella, Navi- 

 cula, and Gomphonema, impart an ochreous hue. Blue 

 proceeds from the Stentor ceruleus. Masses of water 

 assume an intense green from Monas bicolor, Uvella 

 bodo, Glenomorum tingens, Phacelomonas pulvisculus, 



