The progress in physics has suggested the possibility of saving by cold storage processes the healthy organs of persons who have met violent deaths, for transplanting in place of diseased organs in living persons.

In the field of sanitation, it has been proved that, at an expense of less than $3 per year per inhabitant, it is possible to make the miasmatic regions of the Canal Zone as safe as the most carefully guarded city; and since the methods for doing this work have been so worked out that they may be adapted to any locality, one ceases to wonder why liberal men should be ready to give large means, and why men of strong intellects should be attracted to the narrow confines of the laboratory, to devote promising lives to patient study and investigation. It is needless to say that those who are selected to do this work must be men of demonstrated intellectual ability with a capacity for work, and with such a devotion to humanity that they will find their reward in their work, rather than in the monetary returns which these positions pay. One of these will discover the real cause of cancer, and develop a cure for it; another will place himself alongside of Jenner by leading the world to a mastery of tuberculosis; and through the labors of others, one after another of the enemies of humanity which have heretofore baffled science will be controlled.

CHAPTER XXIV.

COMMERCE AND MEDICINE.

Closely related to the work of the research men in medicine is the work of the preparation and distribution of the curative and remedial agents, whose virtues have been discovered in the research laboratories and tried out in the dispensaries and the hospitals, and the manufacture and sale of medical supplies. After Jenner had discovered his treatment for smallpox, through the careless handling of vaccine the treatment was used with only partial success, thus arousing prejudice against it and hindering its use for many years. This has been changed, and the laboratories which supply vaccines, antitoxins, bacterins and tuberculins are now supervised by trained experts.

Not less than forty biological products are used in medicine today, and each is prepared according to its own special methods. The important factor in the preparation of these products is the maintenance of absolute purity and standard of immunizing power, so that the physician may inoculate the patient without any danger of implanting in him the germs of some other disease.

There are in this country today twenty-five of these commercial biological laboratories, all of which are regularly inspected by officers of the federal government.

In the preparation of the antitoxin for diphtheria, young healthy horses are rendered immune to the poison. The toxin is obtained by the development of a virulent

culture of the diphtheria bacilli upon the surface of beef bouillon in a flask at a uniform temperature of 65 degrees Fahr. for one week. The culture is then treated with a 5 per cent. solution of carbolic acid, and after standing for forty-eight hours the solution is filtered. A one-hundredth cubic centimeter is then injected into a 250-gram guinea pig, and if it kills the animal within four days it is considered strong enough to try on the horse. The horse is given an amount of the toxin which would be considered necessary to kill 5,000 guinea pigs of the former weight. At the same time he also receives an injection of 10,000 units of diphtheria antitoxin. This process is repeated with larger doses of the poison, and in three or four days a repetition of the doses of both the toxin and the antitoxin. After this the animal receives, every five days, an injection of the toxin only, and so the conflict between the virulent germs and their enemies is waged in the circulatory system of the animal for about six weeks; after which a little blood serum is withdrawn and its resisting power is tested. If its power is high the horse is bled to death under strict conditions of cleanliness, the blood serum is concentrated, refined, standardized and put into carefully sealed packages for the market.

It is needless to say that great care must be exercised to see that the animals are sound and healthy, that the stables and surroundings are sanitary and that the laboratories and appliances and all the attendants are clean according to the scientific definitions of cleanliness.

Many men who find, after completing their medical course, that they are lacking in some of the qualities which are needful for success in practice, and that they do not possess the imagination nor the initiative for