"I am not sure of that, boys. We may not always be able to find out the exact use of some of these little animals; but that only shows that we are ignorant, not that they are of no use. God would never have made them if he had not some wise purpose in doing so: I do not believe he ever wastes his power in making useless things. But what will you say about gnats, when I tell you that they have a tool to work with, and a very perfect one, too?" "Why, we will almost forgive them for biting us." "Biting you! They have not been biting with teeth: they are doctors, boys; they have only been bleeding you, and cupping you." "And what have they been bleeding us with?" "Why, with a lancet, to be sure; what should a doctor use but a lancet to let blood?" "And has the gnat really a lancet?" "Yes, it has: this instrument forms a part of what you may call the tongue of the gnat: it is made up of five pieces, which are shut up in a case, split from one end to the other; these give steadiness to the lancet when it is used. But the reason of the pain is not so much the wound of the lancet, as it is the fluid or poisonous juice which the gnat puts into the wound to make the blood thin enough for the insect to suck it up through a tube or case, which makes part of its mouth. Here is a drawing of part of a gnat's mouth. [Illustration] And here is a picture of the lancet or knife of a horse-fly. [Illustration] "We have now reached the bridge,--and here we must part; your homes are in one direction, and mine is in the opposite. I hope, however, that you have learned something in our morning's walk." "We have, Uncle Philip, and we thank you much, and bid you, good day." "Good day, boys." CONVERSATION VI. _Uncle Philip tells the Children about Animals that can do Mason's Work._ "Uncle Philip, we saw a very strange thing just now; as we were coming, we saw a great many bees flying by us, and each one was carrying a little stone." "That was strange, indeed. Did you find out any thing about them?" "We asked a man who was near what they did it for, and he said that they carried the stones to prevent the wind, which is blowing pretty fresh, from tossing them about too much." "That is a very silly story, boys, though it is a very old one: for I have seen them carrying what you call stones when it was quite calm, and there was no wind to blow them away. The man was very ignorant, or he would have told you another story, which would have been both strange and true." "Will you have the goodness, Uncle Philip, to tell us what it meant?" "Very willingly, boys. What you saw I presume were bees. You remember that I told you there were several kinds of bees; and this one is called the mason-bee. This kind builds his nest of mortar, and was therefore called the mason-bee by Mr. Reaumur first, I believe." "Where does it get the mortar, Uncle Philip?"