_round at the barn_: It is a common custom with farmers to make this nightly round in order to see that the stock is safe for the night. Were you ever in a barn at night where the horses were still munching hay, and the cattle rattling their stanchions and horns? Recall the picture in Whittier’s “Snow-Bound.” PAGE 83 _diameters_: the unit of measure in the “field” or the lens of the microscope, equivalent to “times.” _white-footed wood mouse_: Text should read _or_ wood mouse. There are other wood mice, but Whitefoot is known as the wood mouse. _gives at the touch_: an idiom, meaning _moves_ back, gives way. _red-backed salamander_: very common under stones; his scientific name is _Plethodon erythronolus_. _His “red” salamander_: Read chapter V in “Pepacton,” by Burroughs. His salamander is the red triton, _Spelerpes ruber_. PAGE 84 _dull ears_: Our ears are dulled by the loud and ceaseless noises of our city life, so that we cannot hear the small voices of nature that doubtless many of the wild creatures are capable of hearing. _tiny tree-frog, Pickering’s hyla_: the one who peeps so shrill from the meadows in spring. “_skirl_”: a Scotch term; see “Tam O’Shanter,” by Burns: “He screwed the pipes and gart them skirl.” _bunches of Christmas fern_: Gathered all through the winter here in the ledges about Mullein Hill by the florists for floral pieces. PAGE 85 _yellow-jacket’s nest_: one of the Vespa Wasps, _Vespa Germanica_. Read the first chapter of “Wasps Social and Solitary,” by G. W. and E. G. Peckham. PAGE 86 _long-tusked boar of the forest_: The wild boar, the ancestor of our domestic pigs is still to be found in the great game preserves in European forests; in this country only in zoölogical gardens. _live in a pen_: How might one, though living in a big modern house, well furnished and ordered, still make a “pen” of it only. CHAPTER XII TO THE TEACHER Notice again that in the three chapters on things to see and do and hear a few of the _characteristic_ sights and sounds and doings have been mentioned. Let the whole teaching of these three chapters be to quicken the pupil to look for and listen for the dominant, characteristic sights and sounds of the season, as he must be trained to look for and listen for the characteristic notes and actions of individual things--birds, animals, flowers. If, for instance, his eye catches the galloping, waving motion of the woodpecker’s flight, if his ear is trained to distinguish the rappings of the same bird on a hollow limb or resonant rail, then the pupil _knows_ that bird and has clues to what is strange in his plumage, his anatomy, his habits, his family traits.