I wonder how many of you know these lines? Not so very long ago most young people used to have to learn the poem from which they are taken, but I don't think the poem can be quite such a favourite as it used to be. Perhaps we are all getting to be such good naturalists that we know it is not quite true, for, though Chamæleons change their colours in a very wonderful way, they do not go red, white, and blue, in the way which the poem makes out. I think I must tell you a little story about a Chamæleon, though some of you may perhaps have heard it before. An old lady once had a pet Chamæleon which she was very fond of, and which her manservant, John, used to look after. He was very fond of the Chamæleon too, and he used to amuse himself by putting it on to different coloured things in his room and watching it change colour. Well, one day, the old lady had a friend to tea, and she thought she would like to show her the Chamæleon, so she rang for John. "John," she said, "bring in the Chamæleon." John looked very sorry for himself. "Please ma'am," he said, "I can't." "Can't?" said his mistress. "Why not?" John looked still more confused. "Please, ma'am," he said, "he's gone." "Why, how is that?" said the lady. "Well, ma'am, I was playing with him, and I put him against my baize apron, and he turned green." "Well?" "And then I put him against the red tray, ma'am, and he turned red." "Yes, yes! Of course he would." "And then I put him against your tartan plaid, ma'am, and--_and he just bust hisself_." [Illustration: YOU CAN SEE HIS EYE LOOKING BACK OVER HIS SHOULDER IN THIS PICTURE] I am afraid that that story is not altogether true either. I must try to explain to you how a Chamæleon changes colour. Of course you all know that there are black men, and brown men, and copper-coloured men, and yellow men, and what we call white men; and you know, too, that among white men some have much darker skins than others. Now the colour of people depends a little on the colour of their blood, for there is a network of tiny veins in the lower part of their skin, but it depends even more on millions of little specks of yellowish and brownish paint which lie in the upper part of their skin. A negro may be as black as your hat outside, but his blood is red all the same, and he looks black because the little specks of paint in the upper part of his skin are very dark and hide the red blood behind them. When people change colour it is because for one cause or another the colour of their blood can be more plainly, or less plainly, seen; and, when this cause is taken away, their old colour returns, for the little specks of paint have not altered in themselves at all. [Illustration: YOU CAN SEE HIS HANDS AND FEET WELL IN THIS PICTURE]