If by any clever process we could separate the nerves of a man from the rest of his body, if we could turn each one of these nerves into something stiff and firm, and

then could stand the entire group on a pedestal in precisely the shape which it had when it did its work in the body, this network of stiff nerves would be so delicate and so closely woven together that we should be able to follow perfectly the outline of the man to whom it belonged. We should know his height, the breadth of his shoulders, the size of head, hands, and feet; while at the same time we should note that

on certain parts of his skin the network was finer and more intricate than on other parts.

If, going further, we should cut that nerve figure open, we should find other great clusters of nerves that showed the outline of every separate organ of the body.

Having seen all this, unless we know the facts of the case, we might give a thousand wild guesses as to what

this wilderness of nerves was for and how it was ever able to control the sensations and the movements of a human being. Some knowledge of the working of the brain will help explain the difficulty to us.

CHAPTER XXXV

THE CENTER OF CONTROL THE BRAIN

Dr. Howell, in his physiology, describes the case of a dog who met with misfortune, lost the upper part of his brain the cerebrum as it is called — and led a singular life ever afterwards.

Those who were studying the case kept the dog alive a year and a half, and they saw that although the animal did not suffer actual pain, still he did not know enough to feed himself; he did not even recognize his food when he saw it; he showed no pleasure when caressed nor any fear when threatened. Not a trick that he had ever learned did he now remember. And as for burying bones for future use, there was no thought of such a thing. Indeed, from the moment he lost his cerebrum until he died he seemed to do no thinking whatever. Memory was so entirely gone that he recalled nothing that he had ever learned. Formerly he had been a clever and sprightly dog, remembering old tricks, learning new ones, stealing bones and burying them, frightening cats, loving his friends and fighting his foes; but from the moment he lost his cerebrum all was changed. Henceforward he was dull, inactive and uninteresting.

In man the cerebrum is even more important. He may lose part of it through disease or accident and still be able to live and think; but if he loses the whole of it, he dies. If it is injured, he suffers in various ways. We have thus come upon the region of the brain that is most vitally connected with our thinking, with our

activity, and with our power to judge what is best for ourselves.

This constantly active and most important part of the nervous system lies just under the skull. It is the largest division of the brain,

is separated into two halves called hemispheres, and the two together make up what is called the cerebrum.

If you ever have a chance, take in your hands a human brain that has been preserved in alcohol, and let a doctor describe it to you. First of all, however, you will notice that the substance itself looks like nothing so much as

a neatly folded, closely packed mass of gray putty, so lifeless and so uninteresting that you may feel like exclaiming:

"Is this the great commander in chief of the body of man! Is this queer-looking stuff the basis of all my thinking and my feeling!"

But let the doctor hold it and explain it to you, part by part. Watch his eyes; listen to his voice as he does it; for they will tell you that to him this lifeless mass is interesting in every smallest division. He will press one part away from another at the surface and you will see that although each can be separated slightly from its neighbor, still all are firmly held together at the center. In his enthusiasm the doctor may also mention one long scientific name after another, each belonging to its own special brain division. But if he is wise he will tell you that for the present you are to remember but two of the names cerebrum and cerebellum.

He will probably mention them in that order, for the cerebrum is larger and higher up, a soft gray cap it seems to be, folded closely in deep creases, overlapping everything below it. Nevertheless the cerebellum is in sight just beneath, at the back of the head. This too is folded and wrinkled and gray.

It may be that you will ask some questions about these deep creases in both cerebrum and cerebellum; and it may be that the doctor will flash back his swift answer,