The antityphoid vaccine, also worked out on mammals and tested on mammals, has practically abolished typhoid fever in soldiers’ camps. It is estimated by the Surgeon General’s office that during the World War it saved the lives of 60,000 men in the American army alone. [Illustration: _On the roof garden of the Home for Destitute Crippled Children, Chicago. Suppose one of these victims of infantile paralysis were your child? Would you hesitate to sacrifice under ether one or more animals if through the knowledge gained the disease could have been prevented, or your child could have recovered without being crippled?_] BENEFITS OF EXPERIMENTATION TO MAN These are only a very few examples from the long list of benefits that have accrued to humanity through the use of living mammals for experimental purposes. I must mention only one more――the recent discovery of a specific treatment for diabetes. Less than two years ago I invited a little girl to go for a bird walk with me that I might give her the pleasure of stroking and feeding a wild bird in its nest. I was particularly eager that she should enjoy that day, because both she and I knew that she had not many days to live. She was doomed to die of diabetes within six months; as a matter of fact she died in less than three months from the date of our walk. I remember thinking that I would give anything I possessed if I could by some miracle restore that child to health. Today, less than two years later, that miracle could be performed, because Dr. F. G. Banting of the University of Toronto, by a brilliant series of experiments on dogs, has completed investigations begun on rabbits by Claude Bernard seventy-five years ago. The story of this wonderful discovery is long, but here are the outstanding facts. It was found that when the pancreas of a dog is removed, the animal at once develops acute diabetes and usually dies of that disease within three or four weeks. Under the microscope the pancreas is seen to be studded with countless little bodies, known as the islands of Langerhans, after the German scientist who discovered them. It was found that these islands secrete a substance quite different from that secreted by the rest of the pancreas, and that it is the absence of this substance, not the absence of the pancreas itself, that causes diabetes. A method was devised for obtaining an extract from these islands of Langerhans, and it was found that when this extract was injected into a dog whose pancreas has been removed it did not die, but got well and continued to be well as long as it was given injections of this extract. After these injections had been proved to be safe by repeated experiments on dogs, they were tried on human patients with startlingly beneficial results. Even when the disease is of long standing, when the patient has reached the very last stage and is in the coma that immediately precedes death, injections of