OF MICROSCOPIC OBJECTS. V3 
slide and allowed to dry naturally, when their characters 
will be very well shown. To obtain anything hke a natural 
appearance, they must be put up in fluid as in Chapter V. 
Next to the Diatomacez, no class of microscopic objects 
has been more looked into of late than the Foraminifera. 
These animals are almost all marine, having a jelly-like body 
enclosed in one or more chambers of shell, which is generally 
composed of carbonate of lime. The shells are made with 
minute orifices, through which the pseudopodia (false feet) 
are extended by which the animal is enabled to lay hold of 
anything to draw itself along. From the possession of these 
orifices they derive their name, as foramen means a door or 
opening. ‘They have been found in every depth of sea 
hitherto sounded, each depth being abundant in certain 
species; the lowest beds containing the greatest number of 
specimens, though with less variation of kinds. In chalk 
they are found in a fossil state, and may readily be shown 
(see Chapter [V.); in limestone and other hard stones they 
are abundant, and some mountains are composed principally 
of these shells. 
The methods of obtaining Foraminifera are various. Many 
may be found upon seaweeds, which should always be ex- 
amined as soon as possible after gathering. They are found 
in masses upon some coasts where the waves have carried 
and left them; but they are to be found the most abundantly 
in sand or mud dredged from the bottom of the sea. They 
must, however, be cleaned and separated from the mass of 
impurity with which they are usually mixed. This may be 
done in various ways, according to the nature of the accom- 
panying matter. If sand alone, as is frequently the case, 
the whole mass must be thoroughly dried, and then stirred 
up in clean water. The sand will soon subside by its own 
weight, but the chambers of the Foraminifera, being filled 
with air, will float upon the surface, and may be skimmed 
of. There is, however, one objection to this mode of pro- 
ceeding—some of these objects are so minute, the chambers 
containing comparatively so small a quantity of air, that 
