INFL'SOBIAL ANIMALCULES. V 



fresh water of Lakes, rivers, pools, springs, and trenches, bnt extends 

 even to tlic briny ocean, to strong acids, tannin, and the fluids con- 

 tained 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 wo breath o may teem mth them and 

 their germs, whilst the gentlest breeze will bo sufficient to waft 

 them in myriads over the distant waters, and to diffuse these living 

 atoms over the face of jSTatui-e. So that, in short, whether wo 

 descend into the deepest mines, where darkness ever reigns, or climb 

 the loftiest mountains, whoso summits glow with almost perpetual 

 simshine, there shall wo find them located alike. 



Although the colouring of water is sometimes derived from the 

 oxides of iron and other mineral or earthy substances, over which it 

 flows, or from the Oseillatoria and other minute Algoo which it con- 

 tains, an intensity of colouring will also be given it by the presence 

 of Infusorial Animalcules. Thus the Astasia imparts a blood-red 

 coloTU", as also the Euglena rtiber ; the Gallionella, Navicicla, and 

 Gomphonema, impart an ochreous hue. Blue proceeds from the 

 Stentor ceruleus. Masses of water assume an intense green from 

 Monas hicolor, TTvella hodo, Glenomonwi tingens, Phacelovionas pulviscuhcs, 

 Cryptomonas glauca, Cryptoglcna conica, Pandorina morum, Gonium 

 pcctorahj Chlamidomonas pulvismlus, Volvox glohator, Astasia and 

 Euglena sanguinea, when young ; Euglena viridis, Chlorogonium 

 euchlorum, and Ophrydium versatile; yellow from the Astasia 

 jlavicans ; a milky tint from the Polytoma uvella, and Ophryoglena 

 atra, when they are numerous. 



The rapid and mysterious transition of colour, occasionally ob- 

 servable in lakes, and which has often created an alarm in the timid 

 minds of the superstitious inhabitants on their borders, the micros- 

 cope has shewn to arise from certain changes in the condition of 

 Infusoiia. Thus, a lake of clear transparent water will assume a 

 green colour in the course of a day ; nay, more, it will become 

 coloured and turbid in the middle of the day, when the sun brings 

 these creatures to the surface, and rapidly devolopos them, or causes 

 their dead bodies to ascend, whilst in the morning and evening, it 

 will a "lain be clear. 



