The next step brings us to the birds. Before they can look after themselves the little birds must learn how to search for food and the kinds of food good for them. They have to learn the habits of their kind of life. The higher you go in the study of animal life the greater seem to be the dangers which surround the young animals and the longer it takes to teach them how to look after themselves and what to do for themselves. The bird family includes not only the robins, larks, sparrows and pigeons, but also the ducks, geese, and chickens, etc. We are all more or less familiar with birds’ eggs, and if not we know what a hen’s egg looks like. The eggs of the bird family are laid in nests, which is the first sign of home building in the animal kingdom. The birds are the first of the large class of warm-blooded animals. The egg here represents again the reproductive power. The eggs, too, form in the body of the female bird, but are laid in a nest which the parent birds build together. Now this is the first step away from the fish family. The fish looks for a suitable place to lay the eggs and then goes off and leaves them. The birds, however, have to make a nest in which to deposit the eggs. The fish, as you remember, depended upon the warm sun shining on the shallow water to hatch out the eggs, thus depending on an outside force to supply the necessary warmth. In the bird family the mother bird must cover the eggs with her own body and keep them warm until they hatch out. Then, too, the father and mother birds feed the young until they are strong enough to fly and find food for themselves, and so the mother and father birds look after their babies until they are old enough to look after themselves. When this time arrives the old birds cease to bother about the young ones altogether. The fishes never act like parents after the baby fishes are born, because the little fish are able to look after themselves right away. The parent birds are a good deal like fathers and mothers for a time, but only so long as it takes them to teach their little bird children to look out for themselves. Then they forget the children completely. It requires but a few days and no parental care to hatch out a family of baby fishes and no attention at all after birth. It requires several weeks and much patience for the parent birds to hatch out their eggs, and it involves care and attention for several weeks to teach baby birds to take care of themselves. This being a father or mother in the animal kingdom becomes a greater responsibility in every step as we get closer to man, and when we reach man we find him to be the most helpless offspring of all at birth, and that it takes more time, care and attention to bring up a human child to maturity than any other animal. What Makes the Hollow Place at One End of a Boiled Egg?