Yet another system we find employed in the case of the grub of the Dragon-fly, which stands almost alone among insects in its power of extracting the necessary oxygen from the water itself. This is one of the most rapacious of living beings, ever upon the watch for prey, and securing its victims, not by stealth and fraud, but by open attack. Its swimming powers, consequently, are of a very high order, and are due to an organ which serves the double purpose of locomotion and respiration, and which is one of the most wonderful pieces of structure to be found in the whole of the insect world. If a dragon-fly grub be even casually examined, a curious five-pointed appendage will be noticed at the extremity of the body. If these five points be carefully separated they will be seen to surround the entrance to a tubular passage, of about the diameter of an ordinary pin. This passage runs throughout almost the entire length of the body, and, by the expansion and contraction of the abdominal muscles, can be opened and closed at will. When open, of course, it is instantly filled with water; when closed, the contents are driven out with some little force. Consequently, the action of the ejected fluid upon the surrounding water drives the insect sharply forward, just as a sky-rocket rises into the air owing to the action of the expelled gases upon the atmosphere. As soon as the effect of the first stroke is at an end a second contraction of the body takes place, and the operation is repeated as often as necessary. The water, while in the swimming tube, however, is exhausted of its oxygen, for the entrances to the respiratory system are inside instead of outside the body, and act in much the same manner as do the gills of a fish. The insect, therefore, is not obliged to visit the surface of the water at all, and can continue to search for prey without interruption. Such are some of the many modifications brought about in insect structure by the requirements of the respiratory organs alone. Each, as will be noticed, is specially adapted to individual wants, and each is absolutely perfect in its own way, insuring a continual supply of oxygen for the purification of the blood, whatever the conditions under which life may be carried on.—_Good Words._ PIERRE'S MOTTO: A CHACUN SELON SON TRAVAIL. A TALK IN A PARISIAN WORKSHOP ABOUT THE UNEQUAL DISTRIBUTION OF WEALTH. “_A chacun selon son travail_, To each man according to his work, that's my way of looking at it. Go by that motto and things will soon come right.” I heard this said, with great emphasis, by Pierre Nigaud to some of his mates as I entered the workshop. I went there every month to collect the contributions to a Provident Insurance Club, to which several of the men belonged. Pierre was on the whole an industrious as well as clever workman, and had joined the club readily, as he thought it right to save something for his wife and children, and to provide for a rainy day, as the saying is.