Il8 TlMEHRI. 
calcareous and siliceous tests of the Animalcules, mixed 
with the remains of other organisms, such as shells, 
corals, fish and minute plants, and with earthy and vol- 
canic debris, are gradually forming rock systems, which 
will probably be the sites of future continents or islands — 
a part which they have played in Nature from the earliest 
ages in the history of the Earth to which we have any 
clue. Geology teaches us that the earliest sedimentary 
rocks with which we are acquainted, are made up, or 
consist largely, of the remains of Animalcules, compara- 
ble to existing forms; and probably many of the derived 
rocks have a similar origin. From those early ages up 
to modern times, Animalcules have played a corres- 
ponding part, and whole formations of immense thick- 
ness and extent have been built up from them. 
Again, the Animalcules serve as food for many of the 
higher animals. Though individually minute, yet in the 
large numbers in which they exist, they form considerable 
masses, and other oceanic surface animals are largely 
dependent on them ; while in the deep sea, where no 
vegetable life exists, they are, relatively, of still greater 
importance. The dead organisms which fall to the bot- 
tom from the surface, moreover, fall as a constant rain of 
Animalcules, and the protoplasmic substance of these is 
preserved for a comparatively long time. This constant 
supply of food material is one of the chief sources of the 
food of deep-sea animals. 
The study of the Animalcules furnishes an inexhaus- 
tible source of interest for scientific and unscientific 
people, for amateur and professional naturalists. From 
this study have been derived some of the most important 
scientific results of modern times — results that have not 
