INFUSORIANS. 
567 
colonies growing on Conferva in stagnant water. When the animal is disturbed, the 
heads droop down towards the stalks. One of the forms most frequently met with 
is Carchesium, whose tiny branched tree-like colonies resemble moulds; but a few 
moments’ inspection will undeceive the observer, for the little white globular stalked 
heads will be seen to be drawn down towards the base of the colony with a rapid 
jerking movement. 
The trumpet-animalcule ( Stentor ) is of comparatively large size, being about 
one-twenty-iifth of an inch in length when extended. It is usually to be found 
fixed by its pointed end on 
the under side of duckweed 
Its form continually alters 
from a small knob when 
contracted, to a trumpet - 
shaped body when extended; 
and when in motion its shape 
continually .changes, being in 
turn ovoid, pyriform, or even 
spherical. The surface is 
corrugated and covered with 
rows of cilia, by means of 
which the animal swims | 
about. The long cilia at 
the upper part form a spiral, 
within the upper margin of 
which lies the mouth - slit. 
The mouth opens into a 
funnel, leading into the sar- 
code of the interior. The 
contractile vacuole lies to 
the right of the mouth-slit, 
and the nucleus forms an 
elongated beaded band along 
the length of the body. The 
ridge of cilia passing down 
vertically is the mouth- 
fringe of a new animalcule 
about to be formed by division. A cleft sinks in obliquely at one side of the ridge 
which assumes a wavy outline and later a spiral; the cleft sinks, till two complete 
animalcules are formed, with one-half of the nucleus, and a contractile vacuole in 
each. New individuals may also arise by the budding off of tiny ciliated embryos 
from the nucleus. The species of trumpet-animalcule most commonly met with is 
of a brilliant green colour; frequently clusters of them are found clinging by their 
pointed ends to the stem of a water-weed. A specimen has been cut into three 
parts, care being taken to leave a fragment of nucleus in each, with the result 
that each part has repaired itself into a complete animal; the central part, for 
instance, developing a head and a tail-end. 
marine animalcule, Acineta (magnified 600 diameters). 
