There is always some one to smile at, somebody to give your chair to, somebody to whom a book, a flower, or even an old paper, will be a boon. These small attentions will open the way to confidence, will make it possible that in need these friends will give you opportunities to help them which, unless you had shown thoughtfulness and regard for them, they could never have done. A quiet, sympathetic look or smile many a time unbars a heart that needs help which you can give. EASY LESSONS IN ANIMAL BIOLOGY. CHAPTER III. SUB-KINGDOM IX.—VERTEBRATA. Though reptiles are generally regarded with aversion, there is much of interest in their natural history, and even they may serve some useful purpose. There are four genera, and about fifteen hundred species. The respiratory organs are the same in all, and are such as belong to air-breathing animals. With few exceptions they are carnivorous; generally sluggish in their habits, and their sensations dull. Nearly all the winter they are in a state of lethargy. [Illustration: FLYING TOAD.] AMPHIBIA.—There are several species of cold blooded amphibious vertebrates which are properly neither fishes nor reptiles, but, having some things in common with both, should be mentioned here. Their respiration is most peculiar, as they have only gills when young, and, when adult, lungs. In their immature state they are fish-like, but develop no fins; and their limbs, when they at length have them, show the same articulations as those of higher animals. These amphibia, in the progress of their development undergo a series of remarkable metamorphoses. They begin life as water-breathing larvæ. In some of the lower orders the gills remain through life; others, when mature, have lungs only. Aquatic Newts, two-legged Mud-Eels, Toads, and Salamanders, are their representatives. The _Batrachia_[1] include the frog, a well known, tailless amphibian. Its metamorphose is peculiar. The ova are deposited in a jelly-like mass at the bottom of the water, and, if the temperature is suitable, develop rapidly. In a few days very interesting microscopic observations are possible. The embryo presents four distinct appearances before leaving the egg, and five more before assuming its complete organization. For a time it seems a soft-skinned, scaleless fish, breathing only as fishes do, and having a long, flexible tail, used as an oar. Then it develops the palmated hind legs, as assistants in its locomotion, the caudal process diminishes, the forelegs protrude, true lungs are developed, the wriggling tadpole is a frog; abjures kinship with its still aquatic relatives, hops to the land, and enters on pursuits befitting its new mode of life. The common frog is well known, and we present one of a different family. It is distinguished by having the ends of its toes dilated into discs, or suckers, by which it sticks to the smooth bark, and is capable of its arboreal life. It is often