14 
ZOOLOGY 
bers on the surface of the sea, and is large enough to be 
seen witli the naked eye.. 
The true Infusoria are covered with cilia^ or hair-like 
processes, by which they glide about over submerged leaves, 
etc. One of the largest and commonest Infusorians is Pa- 
ramechtm. 
Fig. 10 vejiresents Parameciiwi cmidatum. This animal- 
cule is a mass of protoplasm, rGj)resenting a single celL 
In the body-mass are excavated a mouth and a throat lead- 
ing to a so-called stomach or digestive cavity. Two hollows 
in the body form the contractile vesicles, and another cavity 
constitutes the nucleus 
The trumpet-animalcule {Stentor) is large enough to be 
Fig. 11. — Process of fission in Stenfor polymorphiis. h, a new Stentor budding 
out; e, ready to separate from the original one; /, the two in a contracted 
state. 
detected with the unaided eye. This Infusorian attaches 
itself at one end by a stalk, and builds up a slight tube, into 
which it contracts when disturbed. The Stentor maybe 
sometimes observed multiplying by self-division. 
In Stentor polymorpJius the process of self -division takes 
place in two hours. Fig. 11, /, represents the final stage 
when the two individuals swim away separately, each as- 
suming the original adult form, a. 
The bell-animalcules, Vorticella and Epistylis (Fig. 12), 
form patches like white mould on aquatic plants. Their 
nn'^tions as they suddenly contract and shoot out their bells 
is exceedingly interesting. 
Many Infusorians, besides self-dividing, produce ciliated 
