674 Marvels of the Universe 
the skeleton, perforated and 
decorated in innumerable 
ways. But there are helmet- 
shapes, bird-cage patterns, 
crowns, cones, pyramids, etc. 
The skeletons of the Radio- 
laria are of exquisite con- 
struction and are composed 
of translucent flint (silica), 
with the exception of one 
group, at least, the skeletons 
of which are composed of 
strontium sulphate. The 
members of this group— 
the Acantharia—live in the 
upper waters of the ocean 
and seem to have a greater 
range of life, inasmuch as 
they are found in all parts 
of the oceans, from the 
Arctic to the Antarctic Seas. 
The skeletons of this group 
generally consist of twenty 
rods united in a variety of 
ways. No group of animals, 
land or marine, has skeletons 
developed in such a com- 
plexity of form and variety 
of detail as the Radiolaria. 
The simple lfe of these 
exceedingly small creatures 
does not, apparently, de- 
mand, or need, such magni- 
ficent and elaborately con- 
A RADIOLARIAN. structed skeletons. The 
This vase-shaped form was only recently discovered. It was found with other usefulness of such intricate 
varieties distributed over the floors of the Indian and Pacific Oceans. 
and beautiful structures to 
these humble creatures cannot be fully explained by our greatest marine biologists. Stimuli, 
stresses and strains in the ocean waters may account for a good deal, by their internal and external 
action upon the delicate, soft body of the creature, but the wonderful skeleton can hardly be looked 
upon as a response to all these. All its surprising detail, we must endeavour to realize, is com- 
prised “ within the dimensions of a point.” 
Many groups of Radiolaria are adapted to life on the surface of the waters, with power to 
descend to certain limited depths and to come up again. 
According to Brandt, they descend and ascend by functions that are purely hydrostatic. 
In some groups the delicate covering of the animal is supported loosely on the radiating 
skeleton. This covering can be tightened by elastic threads (filaments) and thus raised 
up. This allows the tiny layers of water which surround and enclose small cavities (vacuoles) to 
expand and so raise the creature in the water to a higher level. It can descend again by the 
