104 
THE OCEAN WORLD. 
They were known to the older naturalists, and it is in this group that 
organization is carried to the highest perfection it attains among the 
Infusoria. The Paramecium possess, besides tlieir reticulated and con- 
tractile tegument, cilia disposed in such a manner as to serve at one® 
gated by spontaneous division, as already described. They abound 
as we have said, in stagnant water, or in pure water which is occU' 
pied by aquatic plants, sometimes in such prodigious quantities that 
thej become troublesome. They occur also in flower vases where tb® 
water is not frequently renewed. 
lhe species of this genus have an oblong compressed body, with 
an oblique longitudinal fold, directed towards the mouth, which is 
lateral. They arc sufficiently large to be observed by the common 
lens, or eye-glass. Paramecium aurelia appears chiefly in vegetable 
infusions. It is common in ditches and moats with aquatic plants. 
Humboldt s assertion is fully verified in the case of the Infusoria 
under consideration, which is often found with its parasites. Tbes® 
aie small cieatuies, cylindrical in form, and provided with sucker®' 
Swimming vigorously in the water, they devote themselves to chasing 
the Paramecium. When they have overtaken the fugitive, they 
throw themselves upon it, and establish themselves there. They soon 
multiply in the interior of its body, and their starving progeny such 
and devour the unfortunate animalcule, which serves them at one® 
for dwelling-house and larder. 
Another of the parasites which prey upon the Paramecium, in 
Fig. 36. Paramecium bnrsaria 
(Pritchard). 
for locomotion, for prehension) 
that is, for seizing its food, and ® s 
a means of respiration. They ar® 
furnished with a mouth, at tb® 
bottom of which the whorl excited 
by the cils, determines, according 
to Dujardin, the hollowing out o* 
a cavity, formed after the manner ot 
a cul-dc-sac, and also the formation 
vacuoles with permanent partitions) 
in which are enclosed the substance® 
which the animalcules have swal- 
lowed along with the water. 
The Paramecium are prop®' 
