These topics and questions should be answered from experience with pigeons and observations of their habits and behavior, and from books to be obtained from the school and public libraries. 1. The homing instinct of the common blue pigeon and of carrier pigeons. 2. Nesting habits, number of broods and number of young in each brood, feeding the young. Why is this method of feeding the young necessary? 3. Varieties or breeds of pigeons. How the various varieties were produced; how they are kept true; reversions of type. 4. Darwin's experiments with the pigeons; object of the experiment. Whitman's experiments. The Exoskeleton of the Bird: Plumage _Materials._ Living birds, as perhaps pigeons, or mounted or stuffed skins, separate feathers, portions of feathers, microscopes. _Observations._ The pupils should study the arrangement of the feathers and their variations in form and size, and should identify the following principal kinds:-- _Contour feathers_, those feathers, generally broad, which cover the body, giving to it its outline and color. _Coverts_, those feathers which cover joints, such as the joints of the wing and tail. _Primaries_ or _pinions_, the long stiff feathers of the outside of the wing, used in sustaining the bird in flight. _Secondaries_, the shorter, more symmetrical feathers lying next and over the primaries. _Down_, soft feathers found on young birds and next to the skin on some adults. _Thread feathers_, best seen about the eyes, ears, and beak. _Quill_, the bare stiff portion, one end of which is inserted in the skin. Examine its internal structure. _Vane_, the broad expanded portion, the part ordinarily seen on the bird. _Shaft_, the mid-rib of the vane. _Barbs_, the delicate outgrowths of the shaft making up the vane. _Barbules_, the subdivisions of the barbs, some of which are provided with hooklets. These may well be studied microscopically. _Questions._ 1. How is the plumage arranged to offer least resistance to the air in flight? How does a bird sit when exposed to the wind? 2. In a column write the names of the parts of a feather, and opposite each part state its particular use. 3. Of what use are the hooklets on the barbules? 4. State and explain the peculiar position of the shaft of the primary feather; of that of a contour feather. The plumage of many birds contains all stages of feather specialization, from down to pinion. Find as many of them as you can on your specimen. 5. What reason can you assign for the fluffy base and the compact end of the contour feather? 6. How much of the feather of a full-grown bird seems to be supplied with blood vessels? How does this bloodless or full-blooded condition affect the weight of the feather; of the plumage; of the bird? 7. How would the above condition affect the temperature of the blood and of the body? Would it tend to cool the animal or to conserve its heat?