INFUSORIA, 97 
Monde de la Mer,” ‘ present yet another kind of decomposition. 
If we approach the drop of water in which one swims with the barb 
of a feather dipped in ammonia, the animalcule is arrested in its 
movement, but its cilia continue to move rapidly. All at once, . 
upon some point of its circumference, a notch is formed, which 
increases bit by bit until the whole animal is dissolved. If a drop of 
pure water is added, the decomposition is suddenly stopped, and 
what remains of the animalcule recommences its swimming move- 
ments.” (Dujardin.) 
Life is spread over Nature in such abundance that the smallest 
ae 
Wi 
Fig. 28.—Paramecium aurelia and its Parasites. 
Infusorian has often as its parasite a creature still smaller ; these in 
their turn serving as “a dwelling and pasture ground,” to use 
Humboldt’s words, for still smaller animalcules, as represented in 
Fig. 28—a being parasites in various stages of development ; 4, the 
larger animalcule on which they have established themselves. 
The Infusoria may be divided into two groups—the Flagelliferous 
Infusoria, those, namely, which are provided with flagella, and the 
Ciliale Infusoria, namely, those, provided with vibratile cilia. The 
greater number of the Infusoria belong to the first group, which 
comprehends many families ; our space limits us to the mention here 
of a few typical forms only in each group, selecting those which 
se 
