196 WEST, ON THE MICROSCOPE. 
the figures, preceded by some brief and judicious remarks as 
to the mode of using and nature of the instrument. 
We give an extract as an illustration of the style in which 
this little volume is written : 
“There is considerable difficulty in at once distinguishing between the 
lowest forms of animals and plants. Although the animal generally pos- 
sesses a mouth, and a stomach in which to digest its vegetable food, there 
are some forms of animal life so simple as not to possess either of these 
organs. In the sediment from ponds and rivers there will frequently be 
found small irregular masses of living, moving matter. If these are 
watched, they will be found to move about and change their form constantly. 
As they press themselves slowly along, small portions of vegetable matter, 
or occasionally a diatom, mix apparently with their substance, Cells are 
roduced in their interior, which bud off from the parent, and lead the same 
ife. These creatures are called amebas; and though they have no mouth 
or stomach, they are referred to the animal kingdom. They appear to be 
masses of protein (sarcode) without any cell-wall. If we suppose an ameba 
to assume the form of a disc, and to send forth tentacles, or minute elon- 
gated processes from all sides, we should have the sun animalcule (Aetino- 
phrys Sol). This curious creature bas the power, apparently, of suddenly 
contracting its tentacles, and leaping about in the water. It can also con- 
tract its tentacles over particles of starch and animalcules, and press them 
into the fleshy substance in its centre. ‘This is undoubtedly an animal, but 
it has no mouth or stomach. A large number of such forms present them- 
selves under the microscope. Some of them are covered with an external 
envelope, which they make artificially, by attaching small stones and other 
substances to their external surface, as in the case of the Diflugia ; or they 
may form a regular case, or carapace, of cellulose, as is seen in Arcella. We 
shall meet again with forms resembling these when we take our microscope 
to the sea-side, 
“One of the most common animalcules met with in fresh water, and 
whose presence can easily be ensured by steeping a few stalks of hay in a 
glass of water, is the bell-shaped animalcule. These animalcules, which are 
called Vorticella, are of various sizes. Some are so large that their presence 
can easily be detected by the naked eye, whilst others require the highest 
powers of the microseope. ‘They are all distinguished by having a little 
cup-shaped body, which is placed upon a long stalk. The stalk has the 
peculiar power of contracting in a spiral manner, which the creature does 
when anything disturbs it in the slightest manner. In some species these 
stalks are branched, so that hundreds of these creatures are found on a 
single stem, forming an exceedingly beautiful object with the microscope. 
The stalks of these compound Vorticelle are contracted together, so that 
a large mass, expanding over the whole field of the microseope, suddenly 
disappears, and, ‘like the baseless fabric of a vision leaves not a wreck 
behind. A little patience, however, and the fearful ereatures will onee 
more be seen to expand themselves in all their beauty. The mouth of 
their little cup is surrounded by cilia, which are ia constant movement ; 
and when examined minutely, they will be found to possess two apertures, 
through one of which currents of water pass into the body, and from the 
other pass out. Not unfrequently the cup breaks off its stalk. Jt then 
contracts its mouth, and proceeds to roll about free in the water. Many 
other curious changes in form and condition have been observed in these 
wonderful bell-shaped animalcules.” 
There is also an Appendix, on the Preparation and Mounting 
