92 DESCRIPTION OF [Polygastrica. 



although, when seen in masses with the naked eye, they 

 appear of a whitish hue. They are active and carnivorous, 

 feeding on animal as well as fungoid substances. They 

 are found in water wherein animal matter is held in 

 solution, but as the decomposition of the animal matter 

 proceeds, the animalcules die, and their bodies may be 

 seen rising to the surface of the water, and forming a 

 thicka nd colourless gelatinous stratum. Group 1 in the 

 engraving is magnified 800 diameters. They rarely attain 

 to 1-12,000 of an inch in diameter, and never exceed it. 



2. MoNAs termo (M). The end or limit Monad, so 

 named from its having been supposed to be the limit of 

 animal organization. Active, herbiverous, found in stag- 

 nant water, and increase rapidly where there is an abun- 

 dance of vegetable matter undergoing decomposition. 

 Size 1- 600th, although some are not one half or even a 

 third of that measurement. 



3. MoNAs guttula (M). The drop Monad. — Inactive. 

 May be preserved by drying. Twelve stomach-cells may 

 be seen by the aid of indigo or carmine. Surface appears 

 granulated. Found in vessels of water containing plants 

 or flowers. Size 1 -2300th, or less. 



4. MoNAs vivipara. The viviparous Monad. — Inactive. 

 Found in stagnant water (**), coloured. Size l-620th, 

 or less. 



5. M.O'SAH grandis. The great Monad is of a greenish 

 colour except near the mouth. Proboscis short, l-3rd or 

 l-4th the length of the body. It is sluggish. Found in 

 marsh water, very rare. Size l-430th. 



6. MoNAs Zfico/or. The Two -coloured Monad. — Colour- 

 less, excepting one or two green spots within it, atte- 

 nuated anteriorly. Motion vacillating. Size 1 -1440th. 



