If you look at the “roots” of the oar weed you will see that they are not like those of plants which grow in the ground, but are really very strong suckers. For sea-weeds do not send their roots down into the rock, as land plants do into the ground, but merely cling to the surface. That is why they are so easily torn up by the waves. PLATE XLVI CORALLINE (1) For a great many years naturalists could not make up their minds whether this very pretty sea-weed was really a sea-weed or not. For it possesses the curious power of sucking out lime from the sea-water and building it up round itself, just as the polyps of the madrepores and the corals do: so that when it dies and decays it leaves a kind of chalky skeleton behind it. For this reason it was often supposed to be really a kind of coral. We know now, however, that it is a plant. For if it is placed in acid, which dissolves away this “skeleton,” we find that a true vegetable framework is left behind it. While it is alive the coralline is of a deep purple colour. It is quite a small plant, growing only to a height of four or five inches, and you may find it in quantities on the rocks near low-water mark. PLATE XLVI DULSE (2) This weed is also known as the Dillisk, or Dillosk. I dare say that you have often seen it, for it is quite common on nearly all the rocky parts of our coasts, sometimes growing on the rocks themselves, and sometimes on the larger sea-weeds. In colour, it is a deep, dark red, and if you look down upon it on a bright sunny day, as it grows in a pool of clear sea-water, you may see all kinds of lovely rainbow tints playing over its leaves. The leaves or “fronds” as they are more properly called, are about two inches long and a quarter of an inch wide. [Illustration: PLATE XLVI 1. CORALLINE. 2. DULSE.] The dulse is one of the sea-weeds which are used for food. On many parts of the coast of Ireland it is very largely eaten, both boiled and raw, and some people are so fond of it that they have it for breakfast every day. PLATE XLVII THE GREEN LAVER (1) Another name for this plant is the Sea Lettuce; and certainly, with its broad, bright green, crinkled leaves, it does look rather like a cabbage lettuce. It is a very useful plant to keep in a salt-water aquarium, for its leaves give off little bubbles of oxygen gas, which help to keep the water pure and fit for fishes and other creatures to live in. If you look at it on a bright sunny day you will often find that the leaves are covered all over with these tiny bubbles, which look just like little drops of quicksilver. The green laver is found in abundance on most of our rocky coasts, and is often boiled down into a kind of jelly and used as food. PLATE XLVII THE PURPLE LAVER (2)