336 NATURAL HISTORY. 
Water is taken into the chambers by these tubes, and 
then is forced out, through these same tubes, in jets, 
with such force, often, as to rise to the height of a foot 
or more. The chief office of these chambers seems to be 
to expose the blood of the animal to the air in the water. 
In other words, they are the gills, or the breathing appa- 
ratus. These animals are found on all coasts, commonly 
on rocks, where they can be a part of the time under the 
water and a part of the time out of it. Their habits I 
shall refer to again hereafter. 
578. The radiate arrangement so manifest in the Sea 
Anemones and in the Starfish (§ 17) is not seen so plain- 
ly in many of the other animals of this sub-kingdom ; and 
some of the orders are quite aberrant. In some there is 
a considerable approach to the Articulata. The Star- 
fishes and the Sea Anemones are among the type families 
of the Radiates. 
579. Some of the animals of this sub-kingdom have the 
power of moving about, but most of them, in conformity 
with their plant-like character, are stationary during a 
part or the whole of their existence. In muscular appa- 
ratus, therefore, most of the Radiates, like the Mollusks, 
are in strong contrast with the Articulates. 
580. There is a resemblance to vegetables in still other 
respects besides those already mentioned. When any 
parts of these animals are lost by accident, they are gen- 
erally replaced by a new growth. Besides, there is often 
a new animal produced entire by a sort of budding from 
some part. And even farther than this, in some portions 
of this kingdom the animals are arranged in companies, 
like the parts of a plant, on a common stalk or trunk. 
581. None of these animals have any thing like a head, 
and they have only the senses of touch and taste. The 
senses of sight, hearing, and smell, so far as we can see, 
are wholly absent. For the arrangement of the nervous 
system, I refer you to § 18. 
582. As in most of the Radiates there is a small amount 
