A number of neuropterous insects whose early stages are passed in the water are furnished with branchial tracheæ or false gills. These consist of filaments springing from the sides of the abdominal segments. In the early stages of certain dragon flies the rectum supports epithelial folds which are filled with fine tubes from the tracheal system. Among certain aquatic insects belonging to the order of _Hemiptera_ the creatures reach out the hinder portion of the body to secure air. Dr. Myall, in his very interesting book on the Natural History of Aquatic Insects, says: “A _Nepa_ or a _Ranatra_ may sometimes be seen to creep backward along a submerged weed until the tip of its breathing tube breaks the surface of the water.” The _Aphrophora_ while immersed in the watery fluid, whether secreted by itself or consisting of clear water which has been supplied to it, reaches out for air in a precisely similar manner. Primarily the froth made by this insect not only keeps the body moist, but acts as a protection against its enemies. A number of individuals may often be found in one fleck of froth, and they are entirely hidden from sight while immersed in this way. The viscid character of the fluid secreted insures the retention of the air the insect collects in the form of little bubbles. This peculiar feature must have been a secondary acquisition. The bubbles not only surround the insect and the stem upon which it rests, but flows in a continuous sheet between the ventral plates of the abdomen, and the insect probably utilizes this air in the manner of other air-breathing aquatic larvæ--namely, through its spiracles. As many aquatic larvæ respire in two ways, either inhaling air through the spiracles or by means of branchial leaflets, so _Aphrophora_ may likewise utilize its branchial tufts for the same purpose. For this reason we can understand how each fresh bubble added to the mass may aërate the fluid, so to speak, and thus insure at intervals a fresh supply of oxygen. THE NEGRO SINCE THE CIVIL WAR. BY N. S. SHALER, DEAN OF THE SCIENTIFIC SCHOOL OF HARVARD UNIVERSITY.