The one important object is to make each dovecote so attractive to its pigeon owner that, even from a foreign city or a distant land, they will be homesick to be back again. In other words, the love which pigeons have for their home must help do the work for the man who trains

them.

Dr. Mosso's first step was to force his contented young pigeons from their homes for short trips. On the first ventures they were timid, they seemed distrustful, they stretched their necks and peered around. A few of them, however, being braver, would fly to a neighboring roof and glance about the region; but none stayed out long and all were soon back again, cooing in their dovecotes.

At a second venture, on another day, a few would fly rather high, and move in large circles round and round. Evidently they were studying the landscape and getting the relation of things, for they always ended with a straight, true flight to their homes. It was evident that with each outing of this sort they were gaining a wider view of things.

In the course of time Dr. Mosso dared to take a basket of his pigeons to a place half a mile from home. There he freed them. They rose high in the air, made a few great circles, then flew as before, straight and swift, each to his own habitation.

As weeks passed, the distance from home was increased, until at last these well-trained birds could find their way back from a place three hundred miles away. Older pigeons and younger pigeons were often carried in the same basket to some distant point and there released. All would rise together and take the wide view of river and valley and mountain round about, but it was always the older pigeons that made up their minds most promptly, showed the least hesitation about the direction they were to take, reached home soonest, and were the least tired. The younger birds often arrived hours afterwards and seemed much more exhausted.

It was from these younger ones, then, that Dr. Mosso learned his best lessons for science. A friend would take a carefully selected basket of birds to Bologna or to some other distant city, and at the moment when he opened the basket and let them fly upward, a telegraphic message carried the tidings to Dr. Mosso.

He was thus quite ready to expect the birds, and as the time of their arrival drew near he would take his telescope, go to the top of a neighboring church tower, and watch for their coming. But sometimes they came like

such a flash, like such a stretch of swift-moving beaks, feathers, and feet, that they stood on the roof of the dovecote even before he was sure he had seen them.

The journey from Bologna to Turin is three hundred miles, and, as I have said, every bird is tired after such a flight as that, but the youngest birds showed it most. Sometimes they sat crouched and motionless on the roof for several hours before they began to fly about again, or before they had even energy enough to pop into their dovecote.

Dr. Mosso knew that it was through just such cases as this that he could best make his discoveries and best teach human beings what they need to know. He therefore carefully examined various birds in different ways, giving them no pain whatever from the examination, and he saw that the color of their wing muscles was much darker than that of the pigeons who had not been flying. This proved that an extra supply of blood was crowded into all the small blood vessels of the hard-worked muscles. As we learned, even so long ago as in Good Health, vigorous exercise always sends blood to the exercised region. So it was now with the pigeons.

Next followed the brain examination. It appears that sometimes carrier pigeons are not able to meet the test of their own flying. They reach their destination too exhausted to recover their strength at once. It even

happens that sometimes they die as the result of their great exertion. And what does the brain of an exhausted bird show? Is there any explanation of the apparent failure of the eyesight of the flying quails from Africa? Yes, the explanation was as evident as possible. Every person who studied the case with Dr. Mosso appreciated the situation at a glance, for the brains of these pigeons were as pale as if no blood belonged there. Not so, however, the brain of such pigeons as had stayed at home; for them there was rich red blood, and brains as full of it as yours or mine.

The case was proved. Birds that are exhausted by muscle work have pale brains. Clearly, then, the wing muscles of those African quails had robbed the brain of blood. There had not been enough of it to keep the nerves of sight in active condition. Exhausted birds had, therefore, failed to see the houses and the trees against which they flew.

When he was a boy Dr. Gulick once had an experience quite like that of the quails. It was in connection with a ten-mile bicycle race. For the sake of keeping an eye on his own progress he fastened his watch to the handle-bars, and at the given signal off he started. on his course, to win if possible. For a short time he followed the watch hands as he moved onward, harder and faster. Ere long, however, although he still saw the face of the watch, he could not decide what time it

was. Evidently his brain was not getting blood enough to do its work properly.

He won the race; but long before the end he had given up trying to come to any conclusion about the time.

The lesson from carrier pigeon and bicycle race is that he who wishes to do profitable work with his brain must not expect much of himself while he is doing violent muscular work or immediately after it. No man can do much with a brain that has been robbed of its blood supply.

After a hard day on the athletic field or on the farm tossing hay, suppose a tired boy exclaims, "I'm dead tired!" Shall we advise him never to get so tired again? Certainly not. There are times when physical fatigue is the best thing in the world for any of us. But if that tired boy also says, "I suppose I've got to study my geometry no matter how tired I am," we shall know enough to tell him that it is cruel to his brain to try to make it work when his muscles have robbed it of its nourishment, and that what he learns at such a time is quickly forgotten. We shall advise him to rest for a while, then begin his brain work, knowing that when rested he will probably accomplish twice as much in half the time.

Once again, then, about the boat race. It would be even more foolish to expect to pass an examination