CLASSIFICATION OF PROTOZOA, 41 
VIEW OF THE CLASSIFICATION OF THE PROTOZOA. 
Ciliata. 
(Paramecium.) 
Tentaculata. 
(Acineta.) 
Flagellata. . 
(Monas.) 
. | 
INFUSORIA. 
Radiolaria. 
(Actinophrys.) 
Foraminifera 
(Rotalia,) 
| 
GREGARINIDA, RaIZOPODA. 
MoneERA. 
Laboratory Work.—None of the Protozoa, except the shells of the 
Foraminifera and Radiolaria, can be well preserved after death, and it 
is always better to study any animal alive or freshly killed than when 
preserved in any sort of fluid. Fresh-water Amabe and Monera 
should be looked for on the surface of leaves and the stems of sub- 
merged plants in ponds, pools, and ditches. Many fresh-water Rhizo- 
pods dwell in sphagnum swamps and in damp moss or in shaded pools. 
The marine forms may be gathered with a fine towing net, when the 
surface of the ocean is calm. The commoner Foraminifera will be found 
on shells and stones at low-water mark or in shallow water, but most 
abundantly at greater depths—. ¢., from ten to one hundred fathoms. 
On being placed in water they will, after a period of rest, send out 
their pseudopodia. 
To study their form and development they should be placed in a 
drop of water in an animalcule or aquatic box, and kept in this way 
for several days and even weeks, the box being examined daily, and 
water added if necessary. The shells may be studied by grinding and 
slicing into transverse and longitudinal sections. The animals of 
Miliola and other forms (Rotalia, Teatillaria), on being treated with 
diluted chromic acid and stained with carmine, disclosed to Hertwig a 
well-marked nucleus. The nucleus may also be deeply stained by 
hematoxylin or carmine, and may be clearly demonstrated by acetic 
acid, which tends to destroy the surrounding protoplasm. Much in- 
genuity, mechanical skill, and patience is required in the study of the 
Protozoa, and much yet is to be learned regarding their mode of de- 
velopment: and their structure. 
